PURPOSE: To obtain the subject composition, consisting essentially of a tacky resin composed of a (co)polymer of an acrylic or a methacrylic acid ester, a thermal reaction type crosslinking agent and a specific photoinitiator and capable of reducing adhesive strength by irradiation with ultraviolet rays.

CONSTITUTION: The objective composition consisting essentially of (A) 100 pts.wt. tacky resin composed of a (co)polymer of an acrylic or a methacrylic acid ester, (B) preferably 0.1-3 pts. wt. thermal reaction type crosslinking agent such as an isocyanate compound or a melamine compound and (C) preferably 0.5-3 pts.wt. photoinitiator composed of 3,3',4,4'-tetra-(tert-butyl-oxycarbonyl) benzophenone expressed by formula I (R is formula II).