diff --git a/go/pkg/server/gateway.go b/go/pkg/server/gateway.go
index e97c1a4..4e89b4c 100644
--- a/go/pkg/server/gateway.go
+++ b/go/pkg/server/gateway.go
@@ -177,7 +177,10 @@ func (g *Gateway) forwardCheckRequestMiddleware(next http.Handler) http.Handler
 			if err == nil {
 				dslFound = true
 			}
-			// TODO: 各処理を並列化する
+
+			ch := make(chan []interface{})
+			errCh := make(chan error)
+			numForwarded := 0
 			for _, validation := range validations {
 				validation, ok := validation.(map[string]interface{})
 				if !ok {
@@ -202,69 +205,83 @@ func (g *Gateway) forwardCheckRequestMiddleware(next http.Handler) http.Handler
 				}
 
 				if isForwardNeed {
-					// Find the slave node that can handle validation ID
-					slaveNode, err := g.slaveManager.FindSlave(id)
-					if err != nil {
-						http.Error(w, err.Error(), http.StatusInternalServerError)
-						return
-					}
-
-					var client *http.Client
-					if slaveNode.TLSEnabled {
-						transport := &http.Transport{
-							TLSClientConfig: &tls.Config{},
+					numForwarded++
+					go func(id string, ch chan []interface{}) {
+						// Find the slave node that can handle validation ID
+						slaveNode, err := g.slaveManager.FindSlave(id)
+						if err != nil {
+							errCh <- err
+							return
 						}
-						client = &http.Client{Transport: transport}
-					} else {
-						client = &http.Client{}
-					}
-					client.Timeout = 5 * time.Second
 
-					reqBody := map[string]interface{}{
-						"validations": []interface{}{validation},
-					}
-					body, err := json.Marshal(reqBody)
-					if err != nil {
-						http.Error(w, failure.Translate(err, appError.ErrValidateServiceForwardFailed).Error(), http.StatusInternalServerError)
-						return
-					}
-					req, err := http.NewRequest("POST", slaveNode.Addr+"/v1/check", bytes.NewBuffer(body))
-					if err != nil {
-						http.Error(w, failure.Translate(err, appError.ErrValidateServiceForwardFailed).Error(), http.StatusInternalServerError)
-						return
-					}
-					req.Header.Set("Content-Type", "application/json")
+						var client *http.Client
+						if slaveNode.TLSEnabled {
+							transport := &http.Transport{
+								TLSClientConfig: &tls.Config{},
+							}
+							client = &http.Client{Transport: transport}
+						} else {
+							client = &http.Client{}
+						}
+						client.Timeout = 5 * time.Second
 
-					resp, err := client.Do(req)
-					if err != nil {
-						http.Error(w, failure.Translate(err, appError.ErrValidateServiceForwardFailed).Error(), http.StatusInternalServerError)
-						return
-					}
-					defer resp.Body.Close()
+						reqBody := map[string]interface{}{
+							"validations": []interface{}{validation},
+						}
+						body, err := json.Marshal(reqBody)
+						if err != nil {
+							errCh <- failure.Translate(err, appError.ErrValidateServiceForwardFailed)
+							return
+						}
+						req, err := http.NewRequest("POST", slaveNode.Addr+"/v1/check", bytes.NewBuffer(body))
+						if err != nil {
+							errCh <- failure.Translate(err, appError.ErrValidateServiceForwardFailed)
+							return
+						}
+						req.Header.Set("Content-Type", "application/json")
 
-					if resp.StatusCode != http.StatusOK {
-						http.Error(w, failure.New(appError.ErrValidateServiceForwardFailed, failure.Messagef("Failed to forward the validate request to slave: %d", resp.StatusCode)).Error(), http.StatusInternalServerError)
-						return
-					}
+						resp, err := client.Do(req)
+						if err != nil {
+							errCh <- failure.Translate(err, appError.ErrValidateServiceForwardFailed)
+							return
+						}
+						defer resp.Body.Close()
 
-					var respBody map[string]interface{}
-					if err := json.NewDecoder(resp.Body).Decode(&respBody); err != nil {
-						http.Error(w, failure.Translate(err, appError.ErrValidateServiceForwardFailed).Error(), http.StatusInternalServerError)
-						return
-					}
-					results, ok := respBody["results"].([]interface{})
-					if !ok {
-						http.Error(w, failure.New(appError.ErrValidateServiceForwardFailed, failure.Messagef("results field is invalid")).Error(), http.StatusInternalServerError)
-						return
-					}
-					validationResults = append(validationResults, results...)
+						if resp.StatusCode != http.StatusOK {
+							errCh <- failure.New(appError.ErrValidateServiceForwardFailed, failure.Messagef("Failed to forward the validate request to slave: %d", resp.StatusCode))
+							return
+						}
 
-					g.logger.Info(fmt.Sprintf("⚽️ Request (id:%s) Forwarded to Slave %s", id, slaveNode.Id))
+						var respBody map[string]interface{}
+						if err := json.NewDecoder(resp.Body).Decode(&respBody); err != nil {
+							errCh <- failure.Translate(err, appError.ErrValidateServiceForwardFailed)
+							return
+						}
+						results, ok := respBody["results"].([]interface{})
+						if !ok {
+							errCh <- failure.New(appError.ErrRequestParameterInvalid, failure.Messagef("results field is invalid"))
+							return
+						}
+						ch <- results
+						g.logger.Info(fmt.Sprintf("⚽️ Request (id:%s) Forwarded to Slave %s", id, slaveNode.Id))
+					}(id, ch)
 				} else {
 					modifiedRequestValidations = append(modifiedRequestValidations, validation)
 				}
 			}
 
+			for i := 0; i < numForwarded; i++ {
+				select {
+				case err := <-errCh:
+					http.Error(w, err.Error(), http.StatusInternalServerError)
+					return
+				case results := <-ch:
+					validationResults = append(validationResults, results...)
+				case <-time.After(30 * time.Second):
+					http.Error(w, failure.New(appError.ErrValidateServiceForwardFailed, failure.Message("Timeout")).Error(), http.StatusInternalServerError)
+				}
+			}
+
 			reqBody["validations"] = modifiedRequestValidations
 			modifiedReqBody, err := json.Marshal(reqBody)
 			if err != nil {