A controller assembly is mounted on a side wall surface extending in an upward/downward direction of a hydraulic excavator. The controller assembly includes a controller main body, a first bracket, a second bracket, and a vibration suppressing member. The first bracket is mounted on the side wall surface described above. The second bracket is fixed to the controller main body. The vibration suppressing member supports the first bracket at one end in the upward/downward direction, and supports the second bracket at the other end in the upward/downward direction so as to be movable with respect to the first bracket.