A rotary switch device comprising: a switch case having a terminal base to which a center portion contact and a fixed contact member are fixed, a rotation movable portion rotatable around a center of the terminal base centered on a rotation axis with respect to the switch case, and a switch cover connected to the switch case to cover the rotation movable portion, a movable contact member which is accommodated in an accommodation groove formed in the rotation movable portion, is movable in a direction along the rotation axis and includes a contact protrusion part which is pressed in contact with the center portion contact at one end of the movable contact member and a contact surface at another end of the movable contact member, wherein the movable contact member is operable by the rotation movable portion to rotate around the center portion contact between a conductive rotation position in which the center portion contact and the fixed contact member are short-circuited, and a non-contact state in which the movable contact member is in contact with the center portion contact but the contact surface is not in contact with the fixed contact member; and a support portion which is formed in the terminal base and which supports the movable contact member in the non-contact state when the movable contact member is operated by the rotation movable portion to rotate along a rotation direction around the rotation axis, wherein in the non-contact state of the movable contact member, the support portion slidingly supports an edge corner portion of the contact surface of the movable contact member as a sliding contact portion when the movable contact member is operated by the rotation movable portion to rotate along the rotation direction to the conductive rotation position; characterised in that: the edge corner portion of the contact surface is a corner portion of the contact surface on a side of the contact protrusion part. a switch case having a terminal base to which a center portion contact and a fixed contact member are fixed, a rotation movable portion rotatable around a center of the terminal base centered on a rotation axis with respect to the switch case, and a switch cover connected to the switch case to cover the rotation movable portion, a movable contact member which is accommodated in an accommodation groove formed in the rotation movable portion, is movable in a direction along the rotation axis and includes a contact protrusion part which is pressed in contact with the center portion contact at one end of the movable contact member and a contact surface at another end of the movable contact member, wherein the movable contact member is operable by the rotation movable portion to rotate around the center portion contact between a conductive rotation position in which the center portion contact and the fixed contact member are short-circuited, and a non-contact state in which the movable contact member is in contact with the center portion contact but the contact surface is not in contact with the fixed contact member; and a support portion which is formed in the terminal base and which supports the movable contact member in the non-contact state when the movable contact member is operated by the rotation movable portion to rotate along a rotation direction around the rotation axis, wherein in the non-contact state of the movable contact member, the support portion slidingly supports an edge corner portion of the contact surface of the movable contact member as a sliding contact portion when the movable contact member is operated by the rotation movable portion to rotate along the rotation direction to the conductive rotation position; characterised in that: the edge corner portion of the contact surface is a corner portion of the contact surface on a side of the contact protrusion part.