A magnet is contained in a display housing and is supported by a slidable operating member. A control housing contains a magnetoresistance effect element. Slidable shifting of the operating member causes an external magnetic field in a positive (+) direction and an external magnetic field in a negative (−) direction to enter the magnetoresistance effect element from the magnet at different timings, thereby changing the electric resistance of the magnetoresistance effect element. Accordingly, when the operating member is slidably shifted, a switching operation between predetermined modes is performed on the basis of a change in the resistance of the magnetoresistance effect element.