diff --git a/infra/traq/group.go b/infra/traq/group.go
index 3e3d1938..c0ef2821 100644
--- a/infra/traq/group.go
+++ b/infra/traq/group.go
@@ -1,9 +1,7 @@
 package traq
 
 import (
-	"encoding/json"
-	"fmt"
-	"net/http"
+	"context"
 
 	"github.com/gofrs/uuid"
 	"golang.org/x/oauth2"
@@ -12,51 +10,44 @@ import (
 )
 
 func (repo *TraQRepository) GetGroup(token *oauth2.Token, groupID uuid.UUID) (*traq.UserGroup, error) {
-	URL := fmt.Sprintf("%s/groups/%s", repo.URL, groupID)
-	req, err := http.NewRequest(http.MethodGet, URL, nil)
+	ctx := context.TODO()
+	apiClient := NewAPIClient(ctx, token)
+	group, resp, err := apiClient.GroupApi.GetUserGroup(ctx, groupID.String()).Execute()
 	if err != nil {
 		return nil, err
 	}
-	data, err := repo.doRequest(token, req)
+	err = handleStatusCode(resp.StatusCode)
 	if err != nil {
 		return nil, err
 	}
-
-	group := new(traq.UserGroup)
-	err = json.Unmarshal(data, &group)
 	return group, err
 }
 
-func (repo *TraQRepository) GetAllGroups(token *oauth2.Token) ([]*traq.UserGroup, error) {
-	URL := fmt.Sprintf("%s/groups", repo.URL)
-	req, err := http.NewRequest(http.MethodGet, URL, nil)
+func (repo *TraQRepository) GetAllGroups(token *oauth2.Token) ([]traq.UserGroup, error) {
+	ctx := context.TODO()
+	apiClient := NewAPIClient(ctx, token)
+	groups, resp, err := apiClient.GroupApi.GetUserGroups(ctx).Execute()
 	if err != nil {
 		return nil, err
 	}
-	data, err := repo.doRequest(token, req)
+	err = handleStatusCode(resp.StatusCode)
 	if err != nil {
 		return nil, err
 	}
-
-	groups := make([]*traq.UserGroup, 0)
-	err = json.Unmarshal(data, &groups)
 	return groups, err
 }
 
 func (repo *TraQRepository) GetUserBelongingGroupIDs(token *oauth2.Token, userID uuid.UUID) ([]uuid.UUID, error) {
-	URL := fmt.Sprintf("%s/users/%s", repo.URL, userID)
-	req, err := http.NewRequest(http.MethodGet, URL, nil)
+	ctx := context.TODO()
+	apiClient := NewAPIClient(ctx, token)
+	user, resp, err := apiClient.UserApi.GetUser(ctx, userID.String()).Execute()
 	if err != nil {
 		return nil, err
 	}
-	data, err := repo.doRequest(token, req)
+	err = handleStatusCode(resp.StatusCode)
 	if err != nil {
 		return nil, err
 	}
-	user := new(traq.UserDetail)
-	if err := json.Unmarshal(data, &user); err != nil {
-		return nil, err
-	}
 	groups := make([]uuid.UUID, 0, len(user.Groups))
 	for _, gid := range user.Groups {
 		groupUUID, err := uuid.FromString(gid)
@@ -65,6 +56,5 @@ func (repo *TraQRepository) GetUserBelongingGroupIDs(token *oauth2.Token, userID
 		}
 		groups = append(groups, groupUUID)
 	}
-
 	return groups, err
 }
diff --git a/infra/traq/traq.go b/infra/traq/traq.go
index adfe458d..5162acd3 100644
--- a/infra/traq/traq.go
+++ b/infra/traq/traq.go
@@ -5,8 +5,6 @@ import (
 	"crypto/sha256"
 	"encoding/base64"
 	"errors"
-	"io"
-	"net/http"
 	"net/url"
 
 	"github.com/traPtitech/go-traq"
@@ -66,19 +64,6 @@ func (repo *TraQRepository) GetOAuthToken(query, state, codeVerifier string) (*o
 	return repo.Config.Exchange(ctx, code, option)
 }
 
-func (repo *TraQRepository) doRequest(token *oauth2.Token, req *http.Request) ([]byte, error) {
-	client := repo.Config.Client(context.TODO(), token)
-	resp, err := client.Do(req)
-	if err != nil {
-		return nil, err
-	}
-	err = handleStatusCode(resp.StatusCode)
-	if err != nil {
-		return nil, err
-	}
-	return io.ReadAll(resp.Body)
-}
-
 func NewAPIClient(ctx context.Context, token *oauth2.Token) *traq.APIClient {
 	traqconf := traq.NewConfiguration()
 	conf := TraQDefaultConfig
diff --git a/repository/converter.go b/repository/converter.go
index 2f7f6fb4..5486d67c 100644
--- a/repository/converter.go
+++ b/repository/converter.go
@@ -14,13 +14,11 @@ func ConvPtraqUserToPdomainUser(src *traq.User) (dst *domain.User) {
 	return
 }
 
-func ConvSPtraqUserGroupToSPdomainGroup(src []*traq.UserGroup) (dst []*domain.Group) {
+func ConvSPtraqUserGroupToSPdomainGroup(src []traq.UserGroup) (dst []*domain.Group) {
 	dst = make([]*domain.Group, len(src))
 	for i := range src {
-		if src[i] != nil {
-			dst[i] = new(domain.Group)
-			(*dst[i]) = ConvtraqUserGroupTodomainGroup((*src[i]))
-		}
+		dst[i] = new(domain.Group)
+		(*dst[i]) = ConvtraqUserGroupTodomainGroup(src[i])
 	}
 	return
 }