We developed new photoresponsive polydiacetylene (PR-PDA) molecules by incorporating a photocleavable moiety, 6-nitropiperonyl alcohol (NP) or 4,5-dimethoxy-2-nitrobenzyl alcohol (DMN), into a self-assembling diacetylene molecule. Inducing steric disordering of the assembled PDA molecules by the cleavage of the photoresponsive moiety under 365 nm UV irradiation results in color transition from blue to red and development of red fluorescence, allowing convenient photo patterning. Further writing and erasing of fluorescence patterns are demonstrated toward novel secure information communication and anticounterfeiting applications.