To improve alignment accuracy of an optical element. An alignment device includes an optical element, a base portion that holds the optical element and is supported in a state movable in an X-direction and a Y-direction intersecting with the X-direction, a mechanical driving unit driven by a pressure of a fluid, a member in contact with the base portion pushed by the mechanical driving unit, a stage portion that holds the member and is supported in a state movable in the Y-direction, the mechanical driving unit driven by a pressure of a fluid, and a member in contact with the stage portion pushed by the mechanical driving unit. The optical element has a position: adjusted by a balance between the pushing force by the mechanical driving unit and an elastomeric force in which at least one of the base portion and the member elastically deforms in the X-direction; and adjusted by a balance between the pushing force by the mechanical driving unit and an elastomeric force in which at least one of the stage portion and the member elastically deforms in the Y-direction.