PURPOSE: To prevent wrinkling of a film transferred from occurring onto a surface of molding resin in in-mold molding.

CONSTITUTION: When a patterned film is integrated by melting with the surface of molding resin filled by force fitting in a resin-filling space composed of a mold forming part 19 of a fixed mold 11 and a mold forming part 20 of a movable mold 12, the patterned film is fed between the fixed mold 11 and the movable mold 12 by a film supply mechanism. When the movable mold 12 comes in pressure contact with the fixed mold 11 after the film stops at a specific position, the film is fixed by a film-fixing component 25. At the same time a tension adder 29 fits to a second long groove 27 by approach operation to the fixed mold 11 of the movable mold 12. The tension adder 28 pushes a central part of the film in the fitting. A part covering the mold forming part 20 of the film is prevented from wrinkling by the forcible tension-giving.