A double mode switch device for carrying out a mode sensing operation and a cassette holder ejecting operation of magnetic recording and reproducing apparatus. The switch device includes a circuit board having a mode sensing pattern, a mode sensing gear rotatably mounted on the circuit board and having a mode sensing terminal and a cam slot, a cassette holder eject lever rotatably mounted on the circuit board such that it cooperates with the cam slot of the mode sensing gear to eject the cassette holder, and a mode sensing unit for sensing a mode switching operation in accordance with the rotation of the sensing gear and the eject lever. The mode sensing unit may include an eject sensing pattern of the circuit board and an eject sensing terminal provided on the eject lever to come into selective contact with the eject sensing pattern, or the unit my include a switch provided on the circuit board to cooperate with the eject lever.