A door hinge is provided to slant such that a free end of a door is rotated obliquely upward while the door is opened, and an energizing type balancer to assist an opening/closing operation of the door is provided. A hinge axis of the door hinge slants relative to a vertical line, having an upper side thereof being positioned on an inward side in a vehicle width direction and on a forward side in a vehicle longitudinal direction such that a locus of the free end of the door while the door is opened becomes substantially horizontal or lowers in an opening direction at a point before the door is opened to a maximum open position.