A scanning type exposure apparatus includes a projection optical system which projects a pattern of a reticle onto a wafer, which is held by a wafer chuck, a scanning stage system which scanningly moves the reticle and the wafer synchronously with respect the projection optical system, and an inspection system which automatically inspects influence of particles on at least one of the wafer and on the wafer chuck. The inspection system includes a focus detector which measures a focus state of the wafer and a calculator which calculates outputs of the focus detector.