1. A computer readable storage medium storing a computer-executable program for causing a computer to determine at least one of mask pattern and exposure condition of an exposure apparatus having an illumination optical system for illuminating a mask with light from a light source and a projection optical system for projecting the mask pattern onto a substrate, wherein the program causes the computer to perform calculation of an image of a pattern on an object plane of the projection optical system using information about lateral shift of an image caused by the exposure apparatus, and determination of at least one of the mask pattern and the exposure condition based on a calculation result.