A contact mechanism comprising: a movable contact terminal; a movable contact plate having one end connected to the movable contact terminal and the other end supporting a movable contact (56, 57) integrally fixed thereto, and the movable contact plate being adapted to be drivingly moved in a thickness-wise direction of the movable contact plate by an engagement at a distal end of the movable contact plate with a card to make and break contact with a stationary contact (52, 53), wherein the movable contact plate includes three stacked conductive thin plate springs (61, 65, 67), one conductive thin plate spring of the conductive thin plate springs (61, 65, 67) having a driving elastic tongue at a distal end thereof, characterised by another conductive thin plate spring of the conductive thin plate springs having a pair of returning elastic tongues (67b, 67c) at a distal end thereof; and said card having a driving hole provided on one side and an engaging hole provided on the other side, and the card having driving projections (43, 44) provided on one end of the card and projected in the opposite directions so that it has a substantially T-shape, one driving projection having a greater thickness than the other driving projection so as to prevent the pair of returning elastic tongues (67b, 67c) of the movable contact plate do not contact with the card simultaneously, thereby only one of the returning elastic tongues (67b, 67c) makes a contact with the card while the movable contact plate is being moved toward a condition where the movable contacts (56, 57) and stationary contacts (52, 53) are disconnected. a movable contact terminal; a movable contact plate having one end connected to the movable contact terminal and the other end supporting a movable contact (56, 57) integrally fixed thereto, and the movable contact plate being adapted to be drivingly moved in a thickness-wise direction of the movable contact plate by an engagement at a distal end of the movable contact plate with a card to make and break contact with a stationary contact (52, 53), wherein the movable contact plate includes three stacked conductive thin plate springs (61, 65, 67), one conductive thin plate spring of the conductive thin plate springs (61, 65, 67) having a driving elastic tongue at a distal end thereof, characterised by another conductive thin plate spring of the conductive thin plate springs having a pair of returning elastic tongues (67b, 67c) at a distal end thereof; and said card having a driving hole provided on one side and an engaging hole provided on the other side, and the card having driving projections (43, 44) provided on one end of the card and projected in the opposite directions so that it has a substantially T-shape, one driving projection having a greater thickness than the other driving projection so as to prevent the pair of returning elastic tongues (67b, 67c) of the movable contact plate do not contact with the card simultaneously, thereby only one of the returning elastic tongues (67b, 67c) makes a contact with the card while the movable contact plate is being moved toward a condition where the movable contacts (56, 57) and stationary contacts (52, 53) are disconnected.