To smooth getting in and out a vehicle, even in the case of a narrow parking place or in a place having a high pavement by the side, and to prevent agitation due to a strong wind by sliding forward a front door along a guide rail disposed along the side of a vehicle, and moving the same to the side of a hood to open.

A front door of a vehicle main body 1 is formed to include the side of a hood, and slid in the longitudinal direction to be freely opened and closed. That is, a front door 2a in the close position and a front door 2b in the open position are slid along a car body side upper rail 11 and a door side upper rail 21b slid with the above rail, which are guide rails, and a car body center rail 12 and a door side center rail 22b slid with the above rail. A tire 13 is provided a little inside or the guide rail are bent outward not to abut on the opening and closing front doors. Thus, a satisfactory opening area can be secured so as to improve getting in- and out performance of a vehicle.