An alignment device has a support base attached to a conveying device, and a mounting plate to which a gripping member is attached, and the mounting plate is transferably abutted on a fastening holder that is fixed to the support base. A movable ring fixed to the mounting plate has a sliding part that is transferably engaged with the fastening holder. A first holding mechanism arranged between the fastening holder and the mounting plate locks the mounting plate to the fastening holder. A second holding mechanism provided between the fastening holder and the movable ring cancels a first-direction force of the mounting plate.