In a position detection apparatus which detects the position of an alignment mark, the alignment mark is sensed by a low-magnification image sensing system to acquire a rough position, and a stage is aligned based on the acquired rough position. The alignment mark is sensed by a high-magnification image sensing system to acquire an accurate position. The photoelectric conversion elements of the high- and low-magnification image sensing optical systems are elements whose storage times can be set. A controller determines the signal intensity levels of the photoelectric conversion elements on the basis of electrical signals from the photoelectric conversion elements of the high- and low-magnification image sensing optical systems, and sets storage times appropriate for the photoelectric conversion elements. The position of the alignment mark is detected using signals from the photoelectric conversion elements whose storage times are properly set.