To provide a photomask which can form a resist pattern in a desired shape on a semiconductor substrate having a step and to provide a semiconductor device manufacturing method using the photomask.

This photomask 5 which has a light shield part 5a and a fine pattern 5b is used, the fine pattern 5b of the photomask 5 is arranged at the position corresponding to the step part 3a on the surface of a polycrystalline silicon film 3, and exposure is carried out to make an exposure light beam 6' which is less in intensity than the exposure light beam 6 reaches the step part 3a. Consequently, even if halation is generated at the step part 3a, the exposure of the flank of an unexposed part 4b of resist 4 can be stopped. Therefore, the resist pattern 7 having a desired shape can be formed.