Abstract: An electrical switch of dual in-line package type which includes a switch casing having a housing fitting over a base onto which contact leads forming switch sections of the switch are molded, actuators movably disposed in the corresponding switching sections for selectively connecting and disconnecting the contact leads, and a dust cover to fit over the housing. Each of the actuators has an actuating knob extending through the housing for moving the actuators between first and second positions to turn the switch section on or off, which actuating knob has notched portions which engage a projection formed in the dust cover for preventing erroneous function of the switch, while the base is initially divided into two blocks for subsequent welding to each other to achieve air-tightness and to facilitate assembling work of the switch.