Under 325 nm laser light irradiation at room temperature in oxygen gas, the photoluminescence (PL) intensity of pristine anatase TiO 2 decreases considerably and then it recovers reversibly with the same laser light irradiation at room temperature in vacuum. This result gives important information on the oxygen defects at anatase particle surfaces and may also clarify the origin of largely Stokes shifted broad PL band in pristine anatase. New reversible photoinduced spectral change has been also found in anatase-AgI composites for replacing atmosphere (vacuum ↔ oxygen gas) under 325 nm laser light irradiation at room temperature. This spectral change may arise from the excitation energy transfer between excitons in AgI domain and photoinduced oxygen defects at the anatase particle surfaces.