A transmitter is attached to a wheel of a vehicle and transmits data indicating
a condition of a tire of the vehicle. A mounting structure of the transmitter has
a casing, a pin and a fastener cap. The casing accommodates the transmitter. The
casing has a through hole. The pin is attached to the wheel and inserted into the
through hole of the casing. The fastener cap is fastened to the pin such that the
casing does not come off the pin.
