A projection optical device includes a projection optical system which projects an image of a pattern, a support member attached to the projection optical system, and a plurality of coupling members connected to the support member. The coupling members suspend and support the projection optical system through the support member from an upper direction of the support member. The projection optical device can include a frame to which one end of each of the coupling members is attached, such that the projection optical system hangs from the frame via the support member and the coupling members. A projection optical device also can include a liquid supply which supplies a temperature-controlled liquid to a side surface of a projection optical system utilizing gravity to cause the temperature-controlled liquid to flow along the side surface of the projection optical system.