An exposure apparatus for exposing a pattern of a reticle onto a plate while synchronously scanning the reticle and the plate, said exposure apparatus includes a projection optical system for projecting the pattern of the reticle onto the plate, a measuring part for measuring a position of a surface of a target to be measured in an optical axis direction of the projection optical system, and a controller for controlling the position of the surface of the target in the optical axis direction based on a measurement result by the measuring part, wherein said measuring part measures a position of the same measurement point on the surface of the target plural times, wherein said controller uses, as a measurement value of the same measurement point, an average value of plural measurement results obtained at the same measurement point, and wherein said target is the reticle or the plate.