To provide a vehicle submergence detection device capable of early and securely detecting submergence of a vehicle without separately providing a sensor for submergence detection (water sensor etc.).

In the vehicle K1 having a TPMS including a radio communication means between a vehicle body and a tire, the communication state between the vehicle body and the tire is monitored by a controller 1 (submergence determination means) of the TPMS. On the condition that the state where the communication is impossible has been continued for set time or longer or set frequencies or more, it is determined that submergence of the vehicle occurs. Thus, submergence of the vehicle can be early and securely detected.

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