A sliding door (12) for a vehicle (1) comprises an outer panel (21) defining an outer side surface of the vehicle, and an inner panel (22) joined to the outer panel along an outer periphery thereof, and having a central part spaced from the outer panel (21) on an inboard side of the outer panel. The inner panel includes a first inner wall portion (41, 51) extending forward from a rear edge of the inner panel and having a major plane facing laterally, and a second inner wall portion (42, 52) extending in an inboard direction from a front end of the first inner wall portion and having a major plane facing in a fore and aft direction, and a light emitter (81) or a reflector (91) is affixed to a rear surface of the second inner wall portion so as to irradiate light rearward.