PURPOSE: To obtain an image free from printing stain and having superior printing resistance by imagewise exposing a photosensitive layer contg. diazo resin and developing the exposed layer with a developer contg. at least one kind of org. solvent, at least one kind of alkali agent and water as essential components.

CONSTITUTION: A photosensitive layer contg. diazo resin having anions of an F-contg. org. acid as counter anions and a high molecular compd. is imagewise exposed and developed with a developer contg. at least one kind of org. solvent, at least one kind of alkali agent and water as essential components to form an image. A concrete example of the F-contg. org. acid is fluoroalkylcarboxylic acid such as trifluoroacetic acid. An image free from printing stain and having superior printing resistance can be obtd.