PURPOSE: To make it possible to effectively form a photomask by directly forming an opaque image layer on a photosensitive element by using ink jet printing and colored ink for this ink jet printing.

CONSTITUTION: The photosensitive layer is applied on a base and the active light opaque image layer is formed on the photosensitive layer by the ink jet printing. The opaque image layer consists of the colored ink for ink jet which does not substantially penetrate into the inside of the photosensitive layer and does not react therewith. The photosensitive layer is exposed to active light through the opaque image layer and the exposed photosensitive layer is developed to form an image. In such a case, the photosensitive layer is selectable from a wide range, such as diazo, silver halide, photopolymers and dielectric and electrostatic photographic films. The photosensitive element subjected to image formation is composed of the base, the photosensitive layer and, in some cases, a cover sheet.