Copolymers bearing photoacid generating groups and/or photobase generating groups were dyed after UV irradiation with a dye bath containing both an acid dye and a basic dye. Acetophenone O-acryloyloxime (AAPO) was used as a monomer bearing acyloxy-imino (AOI) group that generates a primary amino group upon irradiation, which is followed by hydrolysis. Phenacylsulfonylstyrene (PSSt) and 1,2,3,4-tetrahydronaphthyli deneamino p-styrenesulfonate (NISS) were chosen as monomers having beta-keto sulfone (beta-KS) and iminosulfonate (IS) groups, respectively, which yielded acid groups when irradiated. Copolymers of AAPO and methyl methacrylate (MMA) were dyed with only the acid dye, and those of PSSt or NISS were dyed with only the basic dye after irradiation. AAPO-PSSt-MMA films became dyeable with the acid dye when irradiated for a short time and with the basic dye with further irradiation. However, AAPO-NISS-MMA copolymers showed the reverse dyeing behavior. IR spectra revealed that AOI groups were photochemically decomposed prior to the beta-KS groups for AAPO-PSSt-MMA, and AOI and IS groups decomposed simultaneously for AAPO-NISS-MMA. These results suggested the possibility of adsorption of different ionic dyes on the films by a change of irradiation time; in fact, color patterns could be obtained in a single staining process using the dye bath.