A back door attached to a rear of a vehicle body includes an inner panel, an outer panel facing the inner panel, a first reinforcing member laid on an outer side of the vehicle body and fixed to the inner panel together with a hinge, and a second reinforcing member including a porous portion and arranged to fill a first space between the first reinforcing member and the outer panel on an outer side in a width direction of the vehicle body from a hinge support that supports the hinge to overlap at least a part of a glass upper edge of a back window glass.