A magnet switch which may be employed in automotive engine starters is provided. The magnet switch includes a metallic terminal which extends through a hole formed in a switch cover to have one of ends thereof protruding outside the cover. The other end of the terminal is connected to an exciting coil to energize it to establish an electric connection between contacts. The magnet switch also includes a cylindrical seal and a stopper. The seal is fit on the end of the terminal to hermetically seal a clearance between the hole and the terminal. The stopper provided on the terminal works to stop the seal from moving to the other end of the terminal, thereby ensuring the stability of installation and sealing performance of the seal in the magnet switch.