PURPOSE: To form a thermally sprayed film on a thermally spraying base material such as thin metallic foil without generating deformation, etc., by forming a back mold of a mounting device for the thermal spraying base material of a porous body having fine open pores.

CONSTITUTION: The thermal spraying base material 1 such as metallic foil having about ≤200μ thickness is mounted to the back mold 2 of the mounting device 2 by means of a lock ring 3, screws 4, etc., and is subjected to thermal spraying. The mold 2 of said device is formed of the porous body having the fine open pores 9. The mold 2 consisting of such porous body can be constituted of metals or ceramics. The good-quality thermally sprayed film is formed without deforming or rupturing the thin metallic film of the material 1 by the heat of the thermal spraying of the above-mentioned mold 2 is used.