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 (RA) 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 (RA) 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 (RA), 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 (RA) 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 (RA) 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 (RA), 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 . <EOS>