Method for manufacturing oxygen sensor

A method for manufacturing an oxygen sensor equipped with an oxygen sensor element comprising a solid electrolyte and Pt coatings, as a pair of electrodes, on both surfaces thereof,

• the method comprising at least steps of:
• providing a Pt coating on at least one of the solid electrolyte surfaces exposed to the gas to be tested so as to form closed pores inside the Pt coating;
• and
• heating the Pt coating provided on at least the surface exposed to the gas to be tested in a gas atmosphere with higher oxygen concentration than that of the atmospheric gas, and
• wherein the step of coating is carried out via non-electrolytic platinum plating, and the closed pores are provided inside the Pt coating by bubbling non-oxidizing gas through a plating solution when conducting non-electrolytic platinum plating.