The photon stimulated gas desorption (PSD) from aluminum is investigated experimentally in relation to the amount of carbon on surface. The photodesorption yield (eta) during the first stage of irradiation is reduced three orders of magnitude by removing carbon on the surface using argon ion etching. The amount of desorbed CH4, CO, and CO2 decreases almost linearly as the carbon is removed. The results indicate that desorbed gas comes from the surface layer on the aluminum, at least in the initial stage of irradiation.