To brake/release a retarder brake in accordance with the operation of an operating lever even though a potentiometer is abnormal in an operating lever device which is provided with the operating lever, the potentiometer and a controller and operates the retarder brake.

This device is provided with the potentiometer 3 for outputting a signal corresponding to the operating angle of the operating lever 2, a switch 4 having 1st and 2nd switching parts 10 and 11 for outputting on and off signals in accordance with the position of the lever 2, and the controller 5 for energizing the solenoid 6a of an electromagnetic proportional pressure reducing valve 6 for outputting fluid pressure to the retarder brake 8 on the basis of the respective signals. The controller 5 energizes the solenoid 6a in accordance with the output signal of the potentiometer 3 when the position of the lever 2 by the output signal of the potentiometer 3 coincides with the position of the lever 2 by the on and off signals of the switch 4, energizes the solenoid 6a by the position based on the on and off signals of the switch 4 when the respective positions are different, and brakes and releases the retarder brake 8 in accordance with the position the lever 2 even though the potentiometer 3 is abnormal.