Desorption behavior of D2O or H2O, as a simulant of HTO, on iron surface covered with thin iron oxide film was studied by photon stimulated desorption (PSD) using deuterium lamp, Hg-Xe lamp and dye laser as photon sources. When the iron was irradiated with photon, water or hydrogen molecules were desorbed. Desorption behavior of water and hydrogen molecules depended on the incident energy of photon. Desorption mechanism of water and hydrogen molecules by photon irradiation is discussed.