Disclosed is a key switch including a key base fitted into a key hole on the frame of a keyboard body, two contact plates fastened inside the key base, a key cap covered on the key base, and a slide supported above a vertical stub tube inside the key base by a spring and having a bottom rod inserted in the bore of the stub tube, wherein the bore of the stub tube pierces through the bottom of the key base, and the bottom rod of the slide is maintained in flush with the bottom of the key base before it is being pressed; each contact plate has a contact leg extended out of the key base through a respective side hole and then bent downwards by 90.degree. angle.