A pillar reinforcement of a center pillar comprises an upper part and a lower part with a boundary line of these parts being positioned below the middle level of the pillar reinforcement. The upper and lower parts respectively include side wall portions which extend along a vehicle side face and pairs of vertical wall portions which extend inwardly from front and rear end portions of the side wall portions. The pair of vertical wall portions of the lower part is slant relative to the vehicle width direction so that the distance between the vertical wall portions becomes wider toward the inward direction, and a slant angle of the pair of vertical wall portions of the lower part is greater than that of the vertical portions of the upper part.