PURPOSE: To reduce a noise generated in the case of resetting a pressed down key top to the original condition.

CONSTITUTION: A stem 3 is integrally fitted to a key top 1 so as to vertically move in a housing 2. Leg parts 4 are provided in the stem 3 or the key top 1 to form hooks 11a in point ends of these leg parts 4. Holes 5a for inserting the leg parts 4 and holes 6a, 8a for inserting the hooks 4a are formed in a rubber 5, a membrane sheet 6 and a mounting plate 8, arranged downward the housing 2, to insert the leg parts 4 and the hooks 4a into these holes. At the time of resetting the key top 1, the stem 3 is lifted by the rubber 5, and the hook 9a comes into contact with a reverse surface of the rubber 5 to reduce generation of a noise.