diff --git a/ISCamRecorder/MainForm.Designer.cs b/ISCamRecorder/MainForm.Designer.cs
index 9236a89..ee80fc8 100644
--- a/ISCamRecorder/MainForm.Designer.cs
+++ b/ISCamRecorder/MainForm.Designer.cs
@@ -201,7 +201,13 @@
             this.chart1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) 
             | System.Windows.Forms.AnchorStyles.Left) 
             | System.Windows.Forms.AnchorStyles.Right)));
-            chartArea1.AxisX.LabelStyle.Format = "hh:mm:ss";
+            chartArea1.AxisX.IsLabelAutoFit = false;
+            chartArea1.AxisX.LabelStyle.Angle = 90;
+            chartArea1.AxisX.LabelStyle.Format = "HH:mm:ss";
+            chartArea1.AxisX.MajorGrid.LineColor = System.Drawing.Color.Gray;
+            chartArea1.AxisY.LabelStyle.Enabled = false;
+            chartArea1.AxisY.MajorGrid.LineColor = System.Drawing.Color.Gray;
+            chartArea1.AxisY.Maximum = 1050D;
             chartArea1.BackColor = System.Drawing.Color.FromArgb(((int)(((byte)(192)))), ((int)(((byte)(255)))), ((int)(((byte)(192)))));
             chartArea1.Name = "ChartArea1";
             chartArea1.Position.Auto = false;
diff --git a/ISCamRecorder/MainForm.cs b/ISCamRecorder/MainForm.cs
index 0798db6..dbe020d 100644
--- a/ISCamRecorder/MainForm.cs
+++ b/ISCamRecorder/MainForm.cs
@@ -18,6 +18,7 @@
     public partial class MainForm : Form {
 
         readonly int PLOT_LENGTH = 200;
+        readonly int PLOT_YAXIS_MIN = 800;
 
         private System.Threading.Timer _UITimer;    // UI更新タイマー
         List<ISCamera> _Cameras = new List<ISCamera> ();    // カメラオブジェクト
@@ -88,9 +89,13 @@
         /// グラフをプロット
         /// </summary>
         private void Plot() {
+            if (_Sensor.Values.Count < 1) return;
             chart1.Series[0].Points.Clear();
             lock (SensorData.Locker) {
                 chart1.Series[0].Points.DataBindXY(_Sensor.Times, _Sensor.Values);
+                var minValue = _Sensor.Values.Min();
+                chart1.ChartAreas[0].AxisY.Minimum = 
+                    minValue < PLOT_YAXIS_MIN ? minValue : PLOT_YAXIS_MIN;
             }
         }