#coding: utf-8

"""
ZetCode wxPython tutorial

In this example, we create a submenu and a menu
separator.

author: Jan Bodnar
website: www.zetcode.com
last modified: April 2018
"""

import wx


class Example(wx.Frame):

    def __init__(self, *args, **kwargs):
        super(Example, self).__init__(*args, **kwargs)

        self.InitUI()

    def InitUI(self):

        menubar = wx.MenuBar()

        fileMenu = wx.Menu()
        fileMenu.Append(wx.ID_NEW, '&New')
        fileMenu.Append(wx.ID_OPEN, '&Open')
        fileMenu.Append(wx.ID_SAVE, '&Save')
        fileMenu.AppendSeparator()

        imp = wx.Menu()
        imp.Append(wx.ID_ANY, 'Import newsfeed list...')
        imp.Append(wx.ID_ANY, 'Import bookmarks...')
        imp.Append(wx.ID_ANY, 'Import mail...')

        #fileMenu.AppendMenu(wx.ID_ANY, 'I&mport', imp)
        fileMenu.AppendSubMenu(imp, 'I&mport')
        #サブメニュ"imp"をfileMenuに追加

        qmi = wx.MenuItem(fileMenu, wx.ID_EXIT, '&Quit\tCtrl+W')
        #fileMenu.AppendItem(qmi)
        fileMenu.Append(qmi)

        self.Bind(wx.EVT_MENU, self.OnQuit, qmi)

        menubar.Append(fileMenu, '&File')
        self.SetMenuBar(menubar)

        self.SetSize((350, 250))
        self.SetTitle('Submenu')
        self.Centre()

    def OnQuit(self, e):
        self.Close()


def main():

    app = wx.App()
    ex = Example(None)
    ex.Show()
    app.MainLoop()


if __name__ == '__main__':
    main()

	実行例