diff --git a/ISCamRecorder/MainForm.Designer.cs b/ISCamRecorder/MainForm.Designer.cs
index e8af59f..f6ff095 100644
--- a/ISCamRecorder/MainForm.Designer.cs
+++ b/ISCamRecorder/MainForm.Designer.cs
@@ -23,6 +23,7 @@
         /// コード エディターで変更しないでください。
         /// </summary>
         private void InitializeComponent() {
+            System.Windows.Forms.DataVisualization.Charting.TextAnnotation textAnnotation1 = new System.Windows.Forms.DataVisualization.Charting.TextAnnotation();
             System.Windows.Forms.DataVisualization.Charting.ChartArea chartArea1 = new System.Windows.Forms.DataVisualization.Charting.ChartArea();
             System.Windows.Forms.DataVisualization.Charting.Series series1 = new System.Windows.Forms.DataVisualization.Charting.Series();
             System.Windows.Forms.DataVisualization.Charting.Series series2 = new System.Windows.Forms.DataVisualization.Charting.Series();
@@ -226,6 +227,13 @@
             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)));
+            textAnnotation1.AnchorX = 50D;
+            textAnnotation1.AnchorY = 80D;
+            textAnnotation1.Font = new System.Drawing.Font("Microsoft Sans Serif", 20.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
+            textAnnotation1.Name = "AnnReverseBlood";
+            textAnnotation1.ShadowOffset = 4;
+            textAnnotation1.Text = "逆血未検出";
+            this.chart1.Annotations.Add(textAnnotation1);
             chartArea1.AxisX.IsLabelAutoFit = false;
             chartArea1.AxisX.LabelStyle.Angle = 90;
             chartArea1.AxisX.LabelStyle.Format = "0.0";
diff --git a/ISCamRecorder/SensorData.cs b/ISCamRecorder/SensorData.cs
index aae9cfa..2cd7c57 100644
--- a/ISCamRecorder/SensorData.cs
+++ b/ISCamRecorder/SensorData.cs
@@ -8,6 +8,8 @@
 using System.Diagnostics;
 using System.IO;
 using System.Windows.Forms;
+using System.Windows.Forms.DataVisualization.Charting;
+using System.Drawing;
 
 namespace ISCamRecorder {
 
@@ -17,6 +19,7 @@
     internal class SensorData {
 
         readonly string SERIAL_PORT_NAME = "USB シリアル";  // デバイス名
+        readonly int NUM_SAMPLES_SET_THRES = 20;            // 逆血検出閾値を決定するサンプル数(20Hz) 
         SerialPort _Serial = null;                          // シリアル通信オブジェクト
         Queue<int> ValuesB = new Queue<int>();               // センサー値
         Queue<int> ValuesR = new Queue<int>();               // センサー値
@@ -30,6 +33,7 @@
         MainForm _MF = null;                          // メインフォームインスタンス
         bool _IsRecoding = false;   // 記録中フラグ
         bool _ClearPlot = false;    // プロット消去フラグ
+        bool _ReverseBlood = false;    // 逆血フラグ
 
         public float FrameRate { get { return _Fps.FrameRate; } }   // FPS値
 
@@ -137,6 +141,12 @@
                 // 表示
                 if (_MF.State != STATE.Exit) {
                     _MF.SensorChart.Invoke((MethodInvoker)delegate {
+                        var an = (TextAnnotation)_MF.SensorChart.Annotations["AnnReverseBlood"];
+                        an.Visible = _IsRecoding;
+                        if (_IsRecoding) {
+                            an.Text = _ReverseBlood ? "逆血あり" : "逆血なし";
+                            an.ForeColor = _ReverseBlood ? Color.OrangeRed : Color.Black;
+                        }
                         _MF.SensorChart.Series[0].Points.Clear();
                         _MF.SensorChart.Series[0].Points.DataBindXY(Times, ValuesB);
                         _MF.SensorChart.Series[1].Points.Clear();
@@ -168,6 +178,7 @@
                     _CsvWriter.WriteLine($"Date,Time,elapsed,B,R,G,IR,switch");
                 }
             }
+            _ReverseBlood = false;
             _ClearPlot = true;
             _IsRecoding = true;
         }
diff --git a/ISCamRecorder/Setting.cs b/ISCamRecorder/Setting.cs
index 6ea15b5..53179e6 100644
--- a/ISCamRecorder/Setting.cs
+++ b/ISCamRecorder/Setting.cs
@@ -37,16 +37,17 @@
             SWTrigger = false;
             SWTriggerFPS = 40F;
             ButtonAction = ACTION.movie;
-            RecCameras = new bool[] { true, true, true, true, true };
             SnapCameras = new bool[] { true, true, true, true, false };
 #if DEBUG
             SaveDir = @"D:\DataDBG";
-            RecodingLimit = 3F;
+            RecodingLimit = 5F;
             MovieRate = 1000;
+            RecCameras = new bool[] { true, false, false, false, false };
 #else
             SaveDir = @"D:\Data";
             RecodingLimit = 30F;
             MovieRate = 5000;
+            RecCameras = new bool[] { true, true, true, true, true };
 #endif
             if (File.Exists(SUBJECT_LIST_FILE)) {
                 using (StreamReader sr = new StreamReader(SUBJECT_LIST_FILE)) {