Abstract: An oxygen sensor comprising a substrate made of a metal oxide and electrodes on the surface of the substrate coming into contact with a reference gas and the surface coming into contact with a measured gas, wherein the electrode on at least one of the surfaces of the substrate comprises a laminate structure of a primary particle formed by metallizing a precious metal onto the surface of the metal oxide particle. According to this construction, the porosity of the electrodes can be increased and the size of the interface with the gas can be. Further, deterioration of the electrodes can be prevented even under conditions which generate thermal sintering. In other words, the response as the well as the durability can be improved.