diff --git a/tcontrol/plot_utility.py b/tcontrol/plot_utility.py
index a6dcf6e68ab261f3123eb0ec4e5b9eb18379885a..d11b8d5d4e7aaa960831fe6aa6c3cab69ac1f6a2 100644
--- a/tcontrol/plot_utility.py
+++ b/tcontrol/plot_utility.py
@@ -84,6 +84,11 @@ class AttachedCursor(widgets.Cursor):
 
 
 def plot_response_curve(y, t, title, continuous=True):
+    if not isinstance(y, np.ndarray):
+        y = np.array(y)
+    if len(y.shape)==2 and y.shape[0]>1:
+        # Multi-output system
+        return plot_responses_curve(y, t, title, continuous)
     fig = plt.figure()
     axes = fig.add_axes([0.1, 0.1, 0.8, 0.8])
     axes.set_xlabel('t/s')
@@ -98,6 +103,25 @@ def plot_response_curve(y, t, title, continuous=True):
     axes.grid()
     plt.show()
 
+def plot_responses_curve(y, t, title, continuous=True):
+    # TODO: no access of output name. 
+    # It should be better if output name is set as ylabel
+    fig = plt.figure()
+    fig.suptitle(title)
+    p = y.shape[0]
+    for i in range(p):
+        ax = plt.subplot(p, 1, i+1)
+        ax.set_xlabel('t/s')
+        ax.set_ylabel('Amplitude')
+        ax.axvline(x=0, color='black')
+        ax.axhline(y=0, color='black')
+        if continuous:
+            ax.plot(t, y[i])
+        else:
+            ax.step(t, y[i], where='post')
+        ax.grid()
+    plt.show()
+
 
 def plot_rlocus(kwargs, roots, system):
     fig, ax = plt.subplots()