TIRE PRESSURE MONITORING SYSTEM

A tire pressure monitoring system includes tire air pressure detectors (4), arranged on tires (2) and configured to transmit a tire air pressure signal including pressure data and a tire ID only when the tire is rotated, and a receiver (13), arranged on a vehicle body (5) and capable of receiving the signal from each tire air pressure detector (4). The receiver (13) includes a tire recognition unit (22) configured to monitor whether or not the signal is received from each tire air pressure detector (4) over fixed periods and during each fixed period, obtain a number of the fixed periods during which the signal is not received for each tire air pressure detector (4), and recognize whether each tire is a traveling tire or a spare tire based on the number of the fixed periods that is obtained for the corresponding tire air pressure detector (4).