Disclosed is a practical long-length door which is particularly for four-seater coupe-type passenger vehicles, and which enables rear-seat passages to get into or out of the vehicle whilst front-seat passengers are seated, and resolves the previously occurring problem whereby when a front-seat passenger and a rear-seat passenger got into or out of the vehicle, the door had to be closed once after either the front or rear-seat passenger had got into or out of the vehicle and then re-opened for the other person to be able to get in or out. The disclosed swing-type, long-length, front-side opening door is provided with a second connection means which is formed from a link, one end of which connects with the rear end section of a vehicle body opening section (5) and the other end of which connects with a door (4), and the door is capable of opening as far as the region in the front-back direction of the two rows of seats (front and rear). The door is a two-stage opening door which carries out transition control between three states: a first door state which is closed, a second door state wherein only the region in the front-back direction of the front seats (2) is open, and a third door state wherein the region in the front-back direction of both the front seats (2) and the rear seats (3) is open.