To provide a uniform and stable dot area modulation image forming method which is nearly independent of a change of ambient humidity in exposure, suppresses a change of exposure humidity dependence before and after storage and reduces unevenness in image density.

In the dot area modulation image forming method in which a silver halide photosensitive material having at least one silver halide emulsion layer on a support is developed after exposure using an exposure system having a function to perform imagewise exposure by scanning exposure on the basis of digital data and a function to measure ambient humidity in a room in which the exposure system has been installed or in the exposure system and to control light exposure on the basis of information on the ambient humidity, the silver halide photosensitive material satisfies A≤0.05 wherein A is represented by equation (1).