PURPOSE: To obtain a sensitive material having high gamma and superior graininess by using a singly dispersed silver halide emulsion to form an emulsion layer and by incorporating a precursor of a photographically useful reagent into the emulsion layer and/or other photographic constituent layer.

CONSTITUTION: A singly dispered silver halide emulsion in used to form an emulsion layer and a precursor of a photographically useful reagent in incorporated into the emulsion layer and/or other photographic constituent layer. The precursor is a compound which is stably present under storage conditions and releases a photographic reagent by the separation of a blocking group at the necessary time during processing. The precursor used may be selected among compounds represented by formulae IWV (where A is a hetero atom substituted known photographic reagent and X is a bivalent timing group bonding to methyl through O, cleaves as X-A during processing, are releases A quickly). The preferred amount of the precursor added is 1×10-8W1×10-1mol per 1mol silver according to the kind of the reagent. Thus, a sensitive material having improved graininess especially in a low density region as well as high sensitivity and high gamma can be obtd.