KEY SWITCH

PROBLEM TO BE SOLVED: To provide a key switch which has a lock mechanism, is made thin, is operated with high precision even when abrasion or the like occurs according to the operating state and the long-term use of the key switch, and has high reliability. SOLUTION: The rotation lock mechanism 30 is provided with a lock member 31 displaceable in the parallel direction with a rotating face perpendicular to the spindle 21 of a cam member 4 and a spring 36 exciting the lock member 31 toward the lock position coupled with the cam member 4. The lock member 31 can be displaced to a lock release position against the spring 36 when it abuts a key 6. An operation hole 6b to be coupled with a switch off operating coupling lug 26 formed on the cam member 4 is formed on the tip side of the key 6. An operation lug 6c abutting the switch off operating coupling lug 26 is provided between the tip of the key 6 and the tip of the operation hole 6b.