diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7286fe1a..b1140c3c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - GenerateDocumentationFile
 - Split files
+- Use EditorBrowsable(EditorBrowsableState.Never) instead of private or internal
 
 ## [1.0.5] - 2020-12-18
 ### Added
diff --git a/Source/AtCoderLibrary/DataStructure/FenwickTree.cs b/Source/AtCoderLibrary/DataStructure/FenwickTree.cs
index af5e3bde..f0c4e4d5 100644
--- a/Source/AtCoderLibrary/DataStructure/FenwickTree.cs
+++ b/Source/AtCoderLibrary/DataStructure/FenwickTree.cs
@@ -1,4 +1,5 @@
-using System.Diagnostics;
+using System.ComponentModel;
+using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using AtCoder.Internal;
 
@@ -24,7 +25,9 @@ public class FenwickTree<TValue, TOp>
         where TOp : struct, IArithmeticOperator<TValue>
     {
         private static readonly TOp op = default;
-        internal readonly TValue[] data;
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public readonly TValue[] data;
 
         public int Length { get; }
 
@@ -76,7 +79,9 @@ public TValue Sum(int l, int r)
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal TValue Sum(int r)
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public TValue Sum(int r)
         {
             TValue s = default;
             for (; r > 0; r -= InternalBit.ExtractLowestSetBit(r))
diff --git a/Source/AtCoderLibrary/DataStructure/LazySegtree.cs b/Source/AtCoderLibrary/DataStructure/LazySegtree.cs
index f89bee1c..aa34dc4c 100644
--- a/Source/AtCoderLibrary/DataStructure/LazySegtree.cs
+++ b/Source/AtCoderLibrary/DataStructure/LazySegtree.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using AtCoder.Internal;
@@ -60,8 +61,10 @@ public class LazySegtree<TValue, F, TOp> where TOp : struct, ILazySegtreeOperato
 
         internal readonly int log;
         internal readonly int size;
-        internal readonly TValue[] d;
-        internal readonly F[] lz;
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public readonly TValue[] d;
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public readonly F[] lz;
 
 
         /// <summary>
@@ -105,10 +108,14 @@ public LazySegtree(TValue[] v) : this(v.Length)
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal void Update(int k) => d[k] = op.Operate(d[2 * k], d[2 * k + 1]);
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public void Update(int k) => d[k] = op.Operate(d[2 * k], d[2 * k + 1]);
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal void AllApply(int k, F f)
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public void AllApply(int k, F f)
         {
             AssertF(f, op.Identity, op.Identity);
             AssertMonoid(d[k]);
@@ -118,7 +125,9 @@ internal void AllApply(int k, F f)
             if (k < size) lz[k] = op.Composition(f, lz[k]);
         }
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal void Push(int k)
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public void Push(int k)
         {
             AllApply(2 * k, lz[k]);
             AllApply(2 * k + 1, lz[k]);
diff --git a/Source/AtCoderLibrary/DataStructure/Segtree.cs b/Source/AtCoderLibrary/DataStructure/Segtree.cs
index b98c7dbd..f02e4bd6 100644
--- a/Source/AtCoderLibrary/DataStructure/Segtree.cs
+++ b/Source/AtCoderLibrary/DataStructure/Segtree.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using AtCoder.Internal;
@@ -47,7 +48,9 @@ public class Segtree<TValue, TOp> where TOp : struct, ISegtreeOperator<TValue>
 
         internal readonly int log;
         internal readonly int size;
-        internal readonly TValue[] d;
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public readonly TValue[] d;
 
 
         /// <summary>
@@ -87,7 +90,8 @@ public Segtree(TValue[] v) : this(v.Length)
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal void Update(int k) => d[k] = op.Operate(d[2 * k], d[2 * k + 1]);
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public void Update(int k) => d[k] = op.Operate(d[2 * k], d[2 * k + 1]);
 
         /// <summary>
         /// a[<paramref name="p"/>] を返します。
diff --git a/Source/AtCoderLibrary/Graph/DSU.cs b/Source/AtCoderLibrary/Graph/DSU.cs
index 1fd502a2..4be4b179 100644
--- a/Source/AtCoderLibrary/Graph/DSU.cs
+++ b/Source/AtCoderLibrary/Graph/DSU.cs
@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.ComponentModel;
 using AtCoder.Internal;
 
 namespace AtCoder
@@ -6,7 +7,9 @@ namespace AtCoder
     public class DSU
     {
         internal readonly int _n;
-        internal readonly int[] _parentOrSize;
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public readonly int[] _parentOrSize;
 
         /// <summary>
         /// <see cref="DSU"/> クラスの新しいインスタンスを、<paramref name="n"/> 頂点 0 辺のグラフとして初期化します。
diff --git a/Source/AtCoderLibrary/Internal/CollectionDebugView.cs b/Source/AtCoderLibrary/Internal/CollectionDebugView.cs
index 72ebfd57..9738426f 100644
--- a/Source/AtCoderLibrary/Internal/CollectionDebugView.cs
+++ b/Source/AtCoderLibrary/Internal/CollectionDebugView.cs
@@ -1,11 +1,14 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.Linq;
 
 namespace AtCoder.Internal
 {
-    internal class CollectionDebugView<T>
+
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    public class CollectionDebugView<T>
     {
         private readonly IEnumerable<T> collection;
         public CollectionDebugView(IEnumerable<T> collection)
@@ -13,6 +16,8 @@ public CollectionDebugView(IEnumerable<T> collection)
             this.collection = collection ?? throw new ArgumentNullException(nameof(collection));
         }
         [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
+#pragma warning disable CA1819 // Properties should not return arrays
         public T[] Items => collection.ToArray();
+#pragma warning restore CA1819 // Properties should not return arrays
     }
 }
diff --git a/Source/AtCoderLibrary/STL/Deque.cs b/Source/AtCoderLibrary/STL/Deque.cs
index 247718ba..e947b03f 100644
--- a/Source/AtCoderLibrary/STL/Deque.cs
+++ b/Source/AtCoderLibrary/STL/Deque.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using AtCoder.Internal;
@@ -11,10 +12,18 @@ namespace AtCoder
     [DebuggerDisplay("Count = {" + nameof(Count) + "}")]
     public class Deque<T> : IEnumerable<T>, IReadOnlyCollection<T>, ICollection<T>
     {
-        internal T[] data;
-        internal int mask;
-        internal int head;
-        internal int tail;
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public T[] data;
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public int mask;
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public int head;
+
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public int tail;
 
         public Deque() : this(8) { }
         public Deque(int capacity)
@@ -60,7 +69,8 @@ public void AddLast(T item)
             if (head == tail) Resize();
         }
 
-        private void Resize()
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public void Resize()
         {
             var oldSize = data.Length;
             var newArray = new T[oldSize << 1];
@@ -122,7 +132,7 @@ public struct Enumerator : IEnumerator<T>, IEnumerable<T>
             int index;
             public readonly int last;
             public T Current => deque.data[index];
-            internal Enumerator(Deque<T> deque, bool isReverse)
+            public Enumerator(Deque<T> deque, bool isReverse)
             {
                 this.deque = deque;
                 this.isReverse = isReverse;
diff --git a/Source/AtCoderLibrary/SourceExpander.Embedder.Config.json b/Source/AtCoderLibrary/SourceExpander.Embedder.Config.json
index 1d7c5190..5f871e2f 100644
--- a/Source/AtCoderLibrary/SourceExpander.Embedder.Config.json
+++ b/Source/AtCoderLibrary/SourceExpander.Embedder.Config.json
@@ -14,6 +14,7 @@
     "System.Diagnostics.DebuggerStepThroughAttribute",
     "System.Diagnostics.DebuggerTypeProxyAttribute",
     "System.Diagnostics.DebuggerVisualizerAttribute",
+    "System.ComponentModel.EditorBrowsableAttribute",
     "AtCoder.IsOperatorAttribute"
   ]
 }
\ No newline at end of file
diff --git a/Source/AtCoderLibrary/Util/DebugUtil.cs b/Source/AtCoderLibrary/Util/DebugUtil.cs
index d70f2464..0a28b567 100644
--- a/Source/AtCoderLibrary/Util/DebugUtil.cs
+++ b/Source/AtCoderLibrary/Util/DebugUtil.cs
@@ -1,9 +1,12 @@
 using System;
+using System.ComponentModel;
 using System.Diagnostics;
 
 namespace AtCoder.Internal
 {
-    internal static class DebugUtil
+
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    public static class DebugUtil
     {
         /// <summary>
         /// if <paramref name="condition"/> is false, throw exception.