Abstract: A rotary switch device in which fixed contacts are fixed to one face side of a base member made of a synthetic resin, contact plates in a ring shape are floatingly held by a rotor disposed opposed to the one face side of the base member, movable contacts capable switching the connection and disconnection to and from the fixed contacts in accordance with the rotation of the rotor are integrally formed at a plurality of places spaced from each other at circumferential intervals on the contact plates, and sliding faces capable of being brought into slide contact with the movable contacts are formed on the one face of the rotor side of the base member, along a plane orthogonal to the rotation axis of the rotor. The sliding faces are formed in the base member so as to avoid the loci which are drawn by portions of the movable contacts to be brought into slide contact with the fixed contacts in accordance with the rotation of the rotor.