To provide a tire pneumatic pressure monitor capable of dividing the case of a radio wave interference and transmitter failure, and reducing useless transmitter exchange.
The tire pneumatic pressure monitor is equipped with transmitters A, B, C, D having pressure sensors 10a, tuners (1), (2), (3), (4) with antennas receiving radio signal from the transmitters A, B, C, D, an ID registration means IDs for respective tires 1, 2, 3, 4 by the memory renewal, and a system failure detection means detecting that it is failure in case of system failure. The system failure detection means is the means which determines that it is not the failure of the transmitters A, B, C, D, but the radio wave interference, when it detects that the previously registered ID has not received two or more simultaneously for a predetermined time.
ITO KAZUHIKO
IWATSUKA TOMONORI
Satoru Asakura