diff --git a/domain/service/cert_service.go b/domain/service/cert_service.go
index a7ce886..a651286 100644
--- a/domain/service/cert_service.go
+++ b/domain/service/cert_service.go
@@ -3,7 +3,6 @@ package service
 import (
 	"autossl/domain/model"
 	"autossl/infrastructure/acme"
-	"autossl/infrastructure/database"
 	"autossl/infrastructure/exception"
 	"autossl/infrastructure/repository"
 	"autossl/infrastructure/util"
@@ -16,9 +15,7 @@ import (
 )
 
 func ExistCert(domain string) bool {
-	repo := &repository.CertRepo{
-		Db: database.Init(),
-	}
+	repo := repository.GetCertRepo()
 
 	byDomain, err := repo.FindByDomain(domain)
 	if err != nil {
@@ -43,9 +40,7 @@ func CreateCert(domain string, code string) error {
 		return err
 	}
 
-	repo := &repository.CertRepo{
-		Db: database.Init(),
-	}
+	repo := repository.GetCertRepo()
 	cert := &model.Cert{
 		Code:   code,
 		Domain: domain,
@@ -79,9 +74,7 @@ func ImportCert(domainName string, certFile *multipart.FileHeader, keyFile *mult
 }
 
 func ListCert() ([]*model.Cert, error) {
-	repo := &repository.CertRepo{
-		Db: database.Init(),
-	}
+	repo := repository.GetCertRepo()
 	list, err := repo.List()
 	if err != nil {
 		return nil, err
@@ -101,9 +94,7 @@ func ListCert() ([]*model.Cert, error) {
 
 func DeleteCert(code string) error {
 	var err error
-	repo := &repository.CertRepo{
-		Db: database.Init(),
-	}
+	repo := repository.GetCertRepo()
 
 	byCode, err := repo.FindByCode(code)
 	if err != nil {
diff --git a/infrastructure/database/connect.go b/infrastructure/database/connect.go
index 5f3acf9..d865e4a 100644
--- a/infrastructure/database/connect.go
+++ b/infrastructure/database/connect.go
@@ -6,10 +6,23 @@ import (
 	"entgo.io/ent/dialect/sql"
 	_ "github.com/mattn/go-sqlite3"
 	"log"
+	"sync"
 	"time"
 )
 
-func Init() *ent.Client {
+var (
+	dbClient *ent.Client
+	once     sync.Once
+)
+
+func GetDBClient() *ent.Client {
+	once.Do(func() {
+		dbClient = initDB()
+	})
+	return dbClient
+}
+
+func initDB() *ent.Client {
 	drv, err := sql.Open(dialect.SQLite, "/root/data/autossl.db?mode=memory&cache=shared&_fk=1")
 	if err != nil {
 		log.Fatalf("failed opening connection to sqlite: %v", err)
diff --git a/infrastructure/repository/cert_repository.go b/infrastructure/repository/cert_repository.go
index 2a6c057..8b08984 100644
--- a/infrastructure/repository/cert_repository.go
+++ b/infrastructure/repository/cert_repository.go
@@ -2,6 +2,7 @@ package repository
 
 import (
 	"autossl/domain/model"
+	"autossl/infrastructure/database"
 	"autossl/infrastructure/ent"
 	"autossl/infrastructure/ent/cert"
 	"context"
@@ -11,6 +12,17 @@ type CertRepo struct {
 	Db *ent.Client
 }
 
+var certRepo *CertRepo
+
+func GetCertRepo() *CertRepo {
+	if certRepo == nil {
+		certRepo = &CertRepo{
+			Db: database.GetDBClient(),
+		}
+	}
+	return certRepo
+}
+
 func (repo *CertRepo) Create(cert *model.Cert) error {
 	_, err := repo.Db.Cert.
 		Create().
diff --git a/main.go b/main.go
index ba3275d..266acf9 100644
--- a/main.go
+++ b/main.go
@@ -30,6 +30,11 @@ func main() {
 
 	// database
 	database.AutoMigrate()
+	defer func() {
+		if err := database.GetDBClient().Close(); err != nil {
+			log.Printf("Failed to close database connection: %v", err)
+		}
+	}()
 
 	// Logger
 	e.Use(config.RequestLogger())