A door for an air conditioner in a vehicle, in which a thin sheet member is joined to a side of a mesh-type frame in such a way as to protrude more than an end portion of the frame so that the protruding portion of the thin sheet member is in contact with the air-conditioning case to thereby promote sealing of the door for opening and closing a passageway of an air-conditioning case, thereby preventing odors caused by molds and reducing material expenses and manufacturing costs by reducing weight of the door.