A fuel synthesis catalyst of an embodiment for hydrogenating a gas includes at least one selected from the group consisting of; carbon dioxide and carbon monoxide, the catalyst comprising, an oxide base material containing at least one oxide selected from the group consisting of; Al2O3, MgO, TiO2, and SiO2, first metal particles containing at least one metal selected from the group consisting of; Ni, Co, Fe, and Cu and brought into contact with the oxide base material, and a porous oxide layer containing at least one selected from the group consisting of; CeO2, ZrO2, TiO2, and SiO2 and having an interface with each of the first metal particles and the oxide base material.