The invention provides a material having a structure including three or more anthracene structures per molecule as a photosensitive unit. That structure allows the material to remain in a liquid state at room temperature due to its reduced crystallinity. After coated on an application member in a liquid state, it is irradiated with light from outside so that it can be cured by way of photocrosslinking, and when heated, it returns back to the original state as the linkage is cleaved. By use of this material it is possible to form a reversibly detachable layer that serves as an adhesive layer at an interface to an application member and a coating layer at the surface of the application member.