Transmitter for tire condition monitoring apparatus

A transmitter (30) is located in a tire of a vehicle and transmits data indicating a tire condition using a carrier wave. The transmitter has an oscillator circuit (31) and a transmission controller (32). The oscillator circuit (31) generates the carrier wave. The transmission controller (32) compensates a deviation of the amplitude of the carrier wave generated by the oscillator circuit relative to a predetermined reference value such that the amplitude of the carrier becomes equal to the reference value. This is capable of maintaining a constant amplitude of a carrier wave.