To develop a functional capsule, which can be controlled to release materials entrapped in the inner aqueous space responding to light, partly crosslinked poly(acrylic acid)-polyethylenimine complex capsules containing a copolymer of acrylic acid and bis[4-(dimethylamino)phenyl] (4-vinylphenyl)methyl leucohydroxide as an additional membrane component with radii of ca. 3 mm have been prepared. The triphenylmethane derivative on the copolymer dissociated into an ion pair under ultraviolet light irradiation in the weak alkaline region. Permeation of p-toluenesulfonate through the capsule membrane was enhanced significantly by the photoirradiation after a several minutes time lag under a weak alkaline condition. The photoinduced increase in permeability of the capsule was pH-dependent. The maximum effect of light on the permeability was observed near pH 8, whereas less enhancement was observed above or below the pH value. When the irradiation of the light was stopped, permeation of the permeant decreased. The photoresponsive permeability change of the capsule membrane can be carried out reversibly.