In an exposure apparatus and method, a mask and a substrate are scanned in synchronism with each other so that the pattern of the mask may be transferred onto the substrate through a projection optical system. First beams of light are irradiated to least two locations on the mask spaced apart in a direction intersecting the scanning direction of the mask. The reflected light thereof is received, and the positions of the points on the mask to which the beam of light has been irradiated are detected in the direction of the optical axis of the projection optical system. In addition, second beams of light are irradiated to at least two locations on the substrate spaced apart in the scanning direction, and the reflected light thereof is received. The positions of the points on the substrate to which the second beam of light has been irradiated are also detected in the direction of the optical axis of the projection optical system are detected. The posture of at least one of the mask and the substrate is adjusted on the basis of the positions detected with the first and second beams.