Tire pressure detecting device

To provide a tire pressure detecting device in which there is no need to perform changing operation of registration information at each time when switching summer tires to winter tires and the like. A tire pressure detecting device includes sensor units (8-12) mounted within wheels of tires (6) of a vehicle for detecting pressure of the tires and wirelessly transmitting information on the detected pressure and predetermined identification information; and a monitoring unit (13) for receiving. transmitted signals from the sensor units (8-12), and, when identification information included in the signals matches the reference information that has been held in advance, determines whether or not the information of the detected pressure included in the signals falls within a normal range, and, if the information does not fall within the normal range, issues a warning, and the characteristic point thereof is in that the identification information and the reference information are information unique to the vehicle (vehicle ID).