Photo-induced methane conversion was examined over Ag-MFI zeolite at room temperature. On the oxidized Ag-MFI zeolite, containing Ag+ exchanged cations, huge amounts of methane were adsorbed, even in the dark, and then converted to mainly ethane upon photo-irradiation without H-2 production. It was revealed that Ag-n(+) small clusters were formed at the expense of Ag+ ion during this photoreaction, and probably hydrogen would be stored as H+ on the ion-exchange sites instead of Ag+. On the other hand, the reduced sample containing larger clusters converted methane into alkene even without photo-irradiation.