To provide a sensor unit registration system for restraining erroneous registration of identification information.

This sensor unit registration system is provided for registering a sensor unit 14 arranged in a tire 13 and intermittently transmitting a radio signal including the pneumatic pressure information of the tire and the identification information proper to itself, in a control device 32 for monitoring pneumatic pressure of the tire based on the radio signals. In the sensor unit registration system, the sensor unit 14 detects a rotation state of the tire 13, and can transmits a counter value of indicting the rotation state by being included in the radio signal, and the control device 32 receives vehicle speed information from a vehicle speed sensor 35, compares the counter value of indicating the vehicle speed state based on the vehicle speed information, with a counter value included in the received radio signal, and registers the identification information included in the radio signal when the counter values coincide with each other.