To provide a method for producing a sensing film for gas sensors by sintering particles comprising a metal or a metal oxide on a substrate, where the sensing film for gas sensors having excellent sensor properties such as sensitivity and responsibility can be easily and simply formed. A nano-meter order particle (100), a dispersant (110) for preventing aggregation of the particles (100), and a scavenger (120) for trapping the dispersant (110) at the sintering are mixed in a solvent (130) to prepare a paste body (140), and this paste body (140) is coated on a base material and fired, thereby forming a sensing film.