To manufacture a key switch having dust protection and waterproof effects, which is capable of changing over a plurality of modes so as to set a plurality of contacts, and an optional numbers of circuits, with low cost using fewer parts.

In a key switch composed of an inner cylinder 2-2 and outer cylinder 2-1 which are freely to rotate relatively by a key, and which is capable of changing over a plurality of modes, an inner sheet 2-4 provided with a plurality of contacts and circuit patterns is disposed being brought into contact with the inner cylinder 2-2. An outer sheet 2-6 provided with a plurality of contacts to a radial direction is disposed being brought into contact with the outer cylinder 2-1, and furthermore a thin sheet (spacer) 2-5 is disposed between the sheet 2-4 and the sheet 2-5 in a circumferential direction on which holes are drilled only on a part corresponding to the contacts.