A vibration-isolating device for a steering wheel of a travelling working vehicle equipped with a wheel steering mechanism includes a first steering shaft (32) that transmits rotational displacement, the first steering shaft being operatively connected to the steering wheel (7); a second steering shaft (33) that transmits rotational displacement, the second steering shaft being operatively connected to the wheel steering mechanism (P, 23); and a vibration-isolating connecting mechanism (31) that operatively connects the first steering shaft (32) and the second steering shaft (33) to each other so that rotational displacement can be transmitted. When the angles of rotational displacement of the first steering shaft (32) and the second steering shaft (33) are within ranges of rotation angles for linearly driving the vehicle, rotational displacement cannot be transmitted between the first steering shaft (32) and the second steering shaft (33).