A side door comprises a door panel portion and a reinforcement portion (a lower-side reinforcement portion and others). The door panel portion is provided to cover an opening portion for entrance and configured such that its peripheral part overlaps with an opening-portion-forming vehicle-body frame member (a side sill and others) in a vehicle side view. The reinforcement portion is provided at the peripheral part of the door panel portion such that it overlaps with the opening-portion-forming vehicle-body frame member in the vehicle side view, thereby reinforcing the peripheral part of the door panel portion against a collision load applied to the side door from a vehicle side. The reinforcement portion is provided at a portion of the peripheral part of the door panel portion which includes a part corresponding to the vehicle-width-direction-extending vehicle-body frame member (a first floor cross member and others).