A clevis pin (connecting pin) (26) is inserted into a clearance hole (72), and is displaceable relative to an operating pedal (16). A pivotal moving link (68) is disposed between the clevis pin (26) and a sensor pin (64) of a load sensor (30). A reaction force applied from the clevis pin (26) to the load sensor (30) always acts in a substantially constant direction (substantially leftward in FIG. 1A) even if the operating pedal (16) and an operating rod (22) are pivoted relatively around the axis of the clevis pin (26) in accordance with the depressing operation of the operating pedal (16). Thus, the detecting accuracy of the load sensor (30) is heightened, and variation in detecting accuracy is prevented, rendering the high reliability.