PURPOSE: To simplify a structure, facilitate size reduction reduce cost, provide high reliability and high durability, and attain nonadjustment and maintenance free.

CONSTITUTION: A leveling valve is provided with an air supply valve part and an air exhaust valve part which supply/discharge compressed air to/from an air spring interposed between a car body frame and a wheel shaft and a supply-discharge switching mechanism 21 which has a rotary shaft 15A to rotate according to a height of a car height and selectively switches so as to open and close the air supply valve part and the air exhaust valve part by interlocking with rotation of the rotary shaft. Therefore, a part 46 to be sensed having a recessed groove is provided on the rotary shaft 15A, and a capacitance type sensor 16A is arranged in a prescribed position corresponding to the part to be sensed, and and a rotary position of the rotary shaft 15A to adjust a car height is detected by sensing the part 46 to be sensed by the sensor.