PURPOSE: To provide an alarm recognizing device which issues an alarm when traffic information displayed on an on-vehicle display device is changed in order to provide display information required for a driver while securing safety for driving.

CONSTITUTION: Multiplex broadcasting is received with an antenna 1 for multiplex broadcasting transmission/reception, a multiplex signal is extracted by an IF conversion part 3, it is decoded by a multiplex decoder 8, thereby, multiplex data is obtained, and the category, map coordinates, and information classification are extracted from the multiplex data by a microcomputer 9, and a control signal is sent to a display controller 12, then, the traffic information is displayed on a display part 13. Thence, the microcomputer 9 discriminates whether or not either of an extracted category, map coordinates, or information classification 23-3 matches a prescribed alarm code. When not, a control signal is sent out to an alarm signal generator 11, and an alarm signal is issued from the alarm signal generator 11.