Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ' ページを初期化するユーザー コードをここに挿入します。
        Call setFocus(Me.txt_code)
        End Sub

 Private Sub setFocus(ByVal ctrl As Control)
        Dim script As String
        script = "<script language='JavaScript'>" & _
                 "        document.getElementById('" & ctrl.ClientID & "').focus();" & _
                 "</script>"
        RegisterStartupScript("setfocus", script)
    End Sub