A method for measuring a spherical aberration or a coma aberration of a projection optical system of an exposure apparatus configured to transfer an image of a pattern formed on an original plate onto a substrate through the projection optical system. The method for measuring the spherical aberration includes obtaining a focal position of the projection optical system under a first measurement condition, obtaining a focal position of the projection optical system under a second measurement condition different from the first measurement condition, and measuring the spherical aberration of the projection optical system based on a difference of the focal position obtained under the first and the second measurement conditions.