To facilitate removal, with a pipe and a hollow and elastic installation part, in a valve stem for gripping a radio tire pressure detector.

A pipe 10 comprises a gas inflow port end 11, a connection end 12, a lower flange 13, an upper flange 14 and an annular groove 15. The lower flange 13 is formed annularly in the pipe and protrudingly in the radial outer direction in the vicinity of a connection end. The upper flange 14 is formed annularly in the pipe and protrudingly in the radial outer direction in the vicinity of the gas inflow port end. An installation body 20 is fixed to an outer peripheral surface of the pipe between both the flanges 13 and 14, and the installation body comprises an engaging part 21, an installation part 22, an installation hole and an annular projection part 26. The engaging part abuts on the lower flange. The installation part is integrally formed with the engaging part, and abuts on the upper flange. The annular projection part is formed protrudingly in the radial inner direction on an inner surface of the installation body, and engages with the annular groove.