In this study, we compared the photodegradation behavior of pentachlorophenol (PCP) and 2,3,4,6-tetrachlorophenol (TeCP) sorbed on polyethylene (PE), polyethylene terephthalate (PET), and polyvinyl chloride (PVC) to investigate the plastic effect. PE accelerated photodegradation of PCP and TeCP, and the photodegradation rate constants on the PE surface were approximately 1.50 times higher than that on a glass surface. In contrast, photodegradation of these organochlorine pollutants on PET was slower than on the glass surface. Furthermore, photodegradation of PCP on the PVC surface was suspended after approximately 60 min of ultraviolet irradiation. These results confirmed that plastics affected the photodegradation behavior of organochlorine pollutants. Lower chlorinated phenols were detected as degradation products, such as di-, tri- and tetra-chlorophenols, thereby confirming occurrence of dechlorination. Fourier transform infrared analysis showed that C = C bonds were produced on PE after UV irradiation, suggesting that PE might act as a hydrogen donor to accelerate photodegradation of PCP and TeCP. For PVC, an increase of the absorbance of the C-CI bond after photodegradation indicated occurrence of chlorine migration, resulting in rechlorination of the intermediate chlorophenols. This study suggests that the characteristics of plastics should be considered for assessment of the fate of organic pollutants sorbed on plastics through phototransformation.