Abstract: A switch compartment 20R is formed in a switch body 20 of electrically insulating material and opens at the top surface of the body. First and second fixed contact members 23C, 24C are secured to the opposed inner walls of the compartment. The open top of the compartment is closed by a cover having a through-bore 32 facing the compartment. An actuator 10 is accommodated in the compartment and outwardly biased by a coil spring 26. The actuator 10 comprises a stem portion 13 protruding through the through-bore and a contact holder block 12 joined to the lower end of the stem portion. The holder block has a housing slot 11 extending therethrough from its front end face to its rear end face. The undersurface of the holder block is formed with a guide slit 18 extending therethrough from the front end face to the rear end face in communication with the housing slot.