PURPOSE: To facilitate attaching and installing works for a switch by deviding the switch into an electrical unit and a mechanical operation unit, attaching a circuit substrate on which the electrical unit is fixed from the back side of a panel, and inserting locking the operation unit from the obverse of the panel.

CONSTITUTION: A switch is devided into an electrical unit including a switch contact 6 and a mechanical operation unit. The electrical unit is arranged and installed on a circuit substrate 2, then the substrate is attached to the back side of the operation panel 1 of an electric device. Then, the operation unit is inserted locked from the obverse of the operation panel 1 of the electrical device so that the electrical unit and the operation unit can be linked and combined together. The work efficiency in attaching and installing the switch to the operation panel 1 can thus be improved, and misconnection to the primary side wiring occurring in the process of attaching the switch can be prevented.