This vehicle body side structure includes a wheel house disposed at a side portion of a vehicle body to surround an upper outer circumference and a vehicle width direction inner side of a wheel, and a damper base fixed to an inner surface of an upper region of the wheel house to support an upper part of a damper of a suspension, in which an upwardly convex three-dimensional curved surface portion curved in all of a side view, a front-rear view, and a vertical view without an inflection point is provided in the upper region of the wheel house, and the damper base is fixed to an inner surface of the three-dimensional curved surface portion.