To obtain a developer which gives a transferred image showing good transfer property and having no defects by incorporating an alkali agent and a fluorine-based surfactant into the developer to be used for an image forming material having a coloring material layer containing pigment on a thermoplastic resin layer.

The image forming material as a coloring material layer containing pigments on a thermoplastic resin on a supporting body. The coloring material layer may be photosensitive or non-photosensitive. When the coloring material layer is non-photosensitive, a photosensitive layer is formed on the coloring layer (in the opposite side to the supporting body). The developer is used for the image forming material having the coloring material layer containing pigments on a thermoplastic resin layer on a supporting body. The image is formed by exposure and development to remove a nonimage part. The developer used contains an alkali agent and a fluorine-based surfactant. The alkali agent is a silicate. The fluorine-based surfactant has ≥0.1 g/l solubility with water.