In order to improve workability of an operation to adjust the interval between two members, leveling devices (3) support an air rail (2) on base frames (1), and adjust the height of the air rail (2) with respect to the base frames (1). The leveling devices (3) have: disc spring groups (31) which expand and contract in the height direction of the air rail (2) with respect to the base frames (1); a columnar indenter (32), in which a stepped through-hole (324) for inserting a bolt (4) is formed from one end face (321) to the other end face (323), with a first edge part (322) formed outward on the one end face (321) side; a columnar spring guide (33), in which a through-hole (334) for inserting the bolt (4) is formed from one end face (331) to the other end face (333), with a flange part (332) formed outward on the one end face (331) side; and a tubular housing (34) in which a second edge part (342) is formed inward at one opening (341) thereof.