An operation tool as a gripping device includes a first arm and a second arm that move in directions opposite to each other, and a third arm for engaging with a workpiece. The operation tool includes a gear and a gear moving cylinder for causing the gear to move to a first position, a second position, and a third position between the first position and the second position. The first arm and the second arm move when the gear is disposed at the first position. The third arm moves when the gear is disposed at the second position. The gear is separated from all of the arms when the gear is disposed at the third position.