An inhibitor switch is disclosed, including a permanent magnet and a magnetic sensor which detects a magnetic force of the permanent magnet in a non-contacting state and outputs a linear change in a voltage value in response to a change in a relative position between the permanent magnet and the magnetic sensor. One of the permanent magnet and the magnetic sensor is mounted on a manual valve shaft side for changing over change gear range positions of an automatic transmission by operating a manual valve of the automatic transmission in an interlocking manner with the manual valve shaft. The other one of the permanent magnet and the magnetic sensor is mounted on a transmission case side of the automatic transmission. The change gear range position of the automatic transmission is detectable in response to an output of the voltage value corresponding to the change gear range position.