A display has a panel display unit with plural display screen portions arranged along a longitudinal direction of a vehicle body and providing an alarm display on a screen, a multistage display unit with reflecting mirrors inclined with respect to the screen portions and arranged at intervals along the longitudinal direction so as to respectively correspond with the screen portions and reflect the alarm display, and an alarm-distance obtaining unit for obtaining an alarm-distance between a present vehicle-position and an alarm-object position. The reflecting mirrors includes a most-rear reflecting mirror and at least one front reflecting mirror through which the alarm display can be seen. A multistage display control unit controls the display unit such that the alarm display is linked to the alarm-distance and provided in display-screen-portion order thereon so as to obtain a deep multistage alarm display.