A vehicle-mounted man-machine interface device comprises display means for displaying a screen, press position detecting means for detecting the press position on the screen, and control means for displaying an operating screen on which operating figures are arranged on the display means and acquiring the operation content specified by the press on the operating screen from the arrangement positions of the operating figures, the operation on each operating figure, and the output of the press position detecting means. The device further comprises traveling detecting means for detecting whether or not the vehicle having the device is traveling or detecting the traveling speed of the vehicle. The control manes sets or alters one or both of the number of operating figures simultaneously displayed on the operating screen and their sizes according to the output from the traveling detecting means. With this, a man-machine interface technique for easily and reliably performing operation can be provided.