A vehicle side body structure can secure a vibration-damping property of a body regardless of design specification by including a rear wheel house including a wheel house outer and a wheel house inner; a side sill extending forward from a front end of the wheel house outer; and an outer reinforcement extending in a vertical direction along a door opening edge from an intermediate portion in a front-rear direction of the wheel house outer. The wheel house outer includes: an outer overhang overhanging outward; and an outer flange extending upward from an inner end of the outer overhang. A reinforcing member is provided to cooperate with the outer overhang and the outer flange so as to define a closed cross section in a substantially triangular shape. The reinforcing member couples a rear end of the side sill and a lower end of the outer reinforcement.