To provide a switch allowing an ON/OFF switching position to be easily adjusted and providing a high durability by suppressing wearing.

In this inhibitor switch for detecting the gear shift position of an automatic transmission, the insulator parts 39 and 39A of an insulator having a sliding surface 93 formed on the surface thereof are projectedly installed on a pole panel, and recessed parts 94 and 94A for reducing surface pressure are provided on the sliding surface 93. When a movable contact 63 is slid relative to a fixed contact S3 to the ON/OFF switching position, the movable contact 63 starts to ride on the insulator parts 39 and 39A so that the movable contact 63 becomes non-contact away from the fixed point S3, and the movable contact 63 is allowed to move from the sliding surface 93 into the recessed parts 94 and 94A. When the movable contact 63 gets down the insulator parts 39 and 39A, the movable contact 63 comes into contact with the ON/OFF switching position of the fixed contact S3.