Each impact-absorbing member has an open cross-sectional shape that is open to a first side of a vehicle width direction. Each impact-absorbing member includes an upper wall, a lower wall, a side wall extending between the upper wall and the lower wall, an upper flange portion extending upward from the upper wall, and a lower flange portion extending downward from the lower wall. Curved portions curved in the vehicle width direction in a protruding manner are formed in the side wall. The upper wall and the lower wall include a plurality of plate-shaped flat portions adjacent in the vehicle width direction, and step portions connecting the adjacent flat portions while forming a step in a vertical direction, respectively.