Public b8_flag As Integer = 0

    Dim startTime As DateTime
    Dim ts As TimeSpan

Private Sub Button8_Click(sender As Object, e As EventArgs) Handles Button8.Click

        Dim startDt As DateTime = DateTime.Now

        If b8_flag = 0 Then
            Button8.Text = "測定停止"

            With ToolStripStatusLabel1
                .Text = "測定中"
                .BackColor = Color.Yellow
            End With
            ToolStripStatusLabel2.Text = "測定時間:00:00:00"
            startTime = DateTime.Now
            Threading.Thread.Sleep(100)
            Timer2.Start()

            b8_flag = 1
        Else
            With ToolStripStatusLabel1
                .Text = "測定停止"
                .BackColor = SystemColors.Control
            End With

            sw.Stop()

            Timer2.Enabled = False
            'ToolStripStatusLabel2.Text = "測定時間:00:00:00"

            b8_flag = 0
        End If
    End Sub

    Private Sub Timer2_Tick(sender As Object, e As EventArgs) Handles Timer2.Tick
        ToolStripStatusLabel2.Text = "測定時間:" & sw.Elapsed.Hours.ToString("00") & ":" & sw.Elapsed.Minutes.ToString("00") & ":" & sw.Elapsed.Seconds.ToString("00")
        ts = Now.Subtract(startTime)    ' 経過時間算出
        ToolStripStatusLabel4.Text = "経過時間:" & ts.TotalMinutes.ToString

        ts = DateTime.Now - startTime
        ToolStripStatusLabel4.Text = String.Format("{0:00}:{1:00}:{2:00}", ts.Hours, ts.Minutes, ts.Seconds)

    End Sub