PURPOSE: To always maintain the specified opened state of a mesh and to obtain a uniform film thickness in a device for depositing the vapor from a vapor soruce to a base body for deposition via the mesh in a vacuum vessel by making horizontally movable the above-mentioned mesh.

CONSTITUTION: The base body 3 is disposed in the vacuum vessel 1 and the vapor source 5 contg. a base material 4 is disposed below the body 3. and the vapor source 5. The vapor is generated when energy is supplied to the source 5. Part of the vapor sticks to the horizontally moving mesh but the rest passes through the mesh and the thin film is formed on the base body 3. On the other hand, the scattering base material particles are blocked by the mesh 8. Since the mesh 8 moves, the undeposited mesh surface is always exposed and therefore the opened state is maintained at all times.