The photoreactions of molecular complexes composed of O3 and three 5-membered heterocyclic compounds, tetrahydrothiophene (THT), pyrrolidine (PyD), and thiazolidine (TAD), are systematically investigated using matrix-isolation infrared (IR) and UV-visible spectroscopies. Two visible-light absorption bands appear in the visible spectra obtained for O3-THT and O3-PyD, whereas four bands are observed for O3-TAD, which contains both N and S atoms in the heterocyclic ring. Upon visible-light irradiation, O3-THT and O3-PyD form their corresponding oxide derivatives, tetrahydrothiophene-1-oxide and pyrrolidine-N-oxide. Although two O3-TAD complexes with different photoreactivities are detected, both structures form thiazolidine-1-oxide upon combining with O and S atom in the heterocyclic ring, but not thiazolidine-N-oxide. The mechanism of formation of these oxide compounds can be explained by the stability of the oxide compound in the triplet state formed via the combination of O(3P) and the paired ring molecule.