SWITCH DEVICE

PROBLEM TO BE SOLVED: To provide a small size switch device used mainly for controlling turning on/off of stop lamps on a vehicle capable of ensuring reliable operation.SOLUTION: A case 11 has a generally columnar magnet 12 mounted on an inner bottom plane with the magnetic direction in a vertical direction, and an opening groove 12A formed in a vertical direction in which a magnetic detecting means 14 is disposed being faced to the magnet 12 including a predetermined space. The magnetic direction of the magnet 12 and the opening groove 12A are arranged in the same vertical direction, and the magnetic poles on the upper and lower faces of the magnet 12 are formed in the same area. With this, the opening groove 12A can be formed with smaller horizontal width dimension and the magnet 12 can be formed smaller. Thus, a smaller size switch device ensuring reliable operation is obtained.