The hydraulic excavator comprises a revolving frame, a boom, a rotary encoder, and a link member. The revolving frame has a base plate and a first vertical plate and second vertical plate that are opposite each other and rise from the base plate. The boom is rotatably supported by the first vertical plate and the second vertical plate. The rotary encoder is provided at a position that is different from a position of the rotational axis of the boom, and senses the rotational angle of the boom according to the rotation of the boom. The link member transmits displacement of the boom to the rotary encoder.