A stage apparatus includes a plate-like stage plate having a spread in a first direction and a second direction intersecting with the first direction and a plate member having a linear expansion coefficient different from that of the stage plate. The stage apparatus includes: a first holding unit configured to hold the plate member on the stage plate; a second holding unit configured to hold the plate member on the stage plate, allow relative deformation caused between the stage plate and the plate member in the first direction, and constrain the relative deformation in the second direction; and a third holding unit configured to hold the plate member on the stage plate, constrain the deformation in the first direction, and allow the deformation in the second direction.