PURPOSE: To provide antenna fitting structure for a tire inflation pressure detector, enabling a user himself to easily fit an antenna used in a tire inflation pressure alarm system.

CONSTITUTION: Antenna fitting structure for a tire inflation pressure detector S is composed of a fixing part 2 where an antenna fixture 1 with an antenna A fitted between a tire wheel W and a brake rotor B fitted to an axle is fixed between the tire wheel W and the brake rotor B, and an antenna supporting part 4 rotatably provided at the periphery of the fixing part 2 through a bearing 3. The antenna A is disposed at the antenna supporting part 2 so as to face the tire inflation pressure detector S, and the rotation of the antenna supporting part 4 is restricted by a restricting member 9 fixed to the body side.