A damper housing includes an upper-wall-plate and an upper-wall-reinforcement-plate. A plurality of collars through which fastening members for attaching a damper are interposed between the upper-wall-plate and the upper-wall-reinforcement-plate. The collars are disposed on a circumference around the damper. An upper section of the damper is fastened and fixed to the upper-wall-reinforcement-plate and the upper-wall-plate by the fastening members. A concave section is formed in at least one of the upper-wall-plate and the upper-wall-reinforcement-plate which are facing each other, the concave section being formed so as to protrude toward the facing upper-wall-plate or the upper-wall-reinforcement-plate. The concave section is disposed between the neighboring collars on the circumference on which the collars are disposed. The upper-wall-plate and the upper-wall-reinforcement-plate are coupled to the facing upper-wall-plate or the upper-wall-reinforcement-plate at the concave section.