A stage apparatus in which a movable stage is guided in first and second directions orthogonal to each other on a stationary member, includes a pair of first elongated holes formed on one of the movable stage and the stationary member and are elongated in the first direction; a pair of link members having two engaging pins at first ends thereof which are engaged in the pair of first elongated holes to be movable therein, respectively, one of second ends of the pair of link members being pivoted at the other of the movable stage and the stationary member, and the other of the second ends of the pair of link members being supported by the other of the movable stage and the stationary member; and a link-member support mechanism for moving the movable stage in the second direction while maintaining a symmetrical shape thereof.