A middle pillar trim and a rear pillar trim positioned to the front and rear of a side window glass are each harder than a roof trim. A curtain air bag fixed to a rear pillar is deployed in a vehicle cabin while a predetermined end edge of the front of the rear pillar trim in the widthwise direction of a vehicle is deformed toward the front. The separation distance of the curtain air bag in a stored state from the side window glass in the widthwise direction of the vehicle is L1 (L2) in the portion of the curtain air bag along the rear edge of the side window glass, and L4 in the portion of the curtain air bag at the upper edge of the side window glass near the middle pillar trim, and the separation distance L1(L2) is smaller than the separation distance L4.