PURPOSE: To reduce the whole height and thickness of a key switch and enhance manufacturing property by providing a pair of locking leg parts, a pair of locking recessed parts, and a guiding inclined surface.

CONSTITUTION: A key top 53 has a pair of locking leg parts 58 having tapered inclined surfaces 59 extending on both sides from the upper part to the lower part, which surfaces are formed toward the upper surface direction. A switch base part 52 has a pair of locking recessed part 62 having tapered inclined surfaces 61 extending on both sides from the upper part to the lower part, which surfaces are formed toward the lower surface direction, and guide inclined surfaces 65 reaching the bottom surface direction of the recessed parts 62 from the lower part to the upper part, which surfaces are provided on both sides of the recessed parts 62. The parts 58 are pushed down along the surfaces 65 of the base part 52, curved and deformed, the surfaces 59 are engaged with the surfaces 61 of the recessed parts 62 of the base part 52 to elastically return the part 58, and the faces 59, 61 make contact to each other, whereby the upward movement of the top 53 is locked to the base part 52. Thus, the whole height of a switch 51 is reduced to allow its thinning, and manufacturing property can be improved.