The present invention provides a resin film for a film capacitor making it possible to obtain the excellent heat resistance, materialize a reduction in a size of the film capacitor and an increase in a capacity thereof and satisfy a reduction in a thickness of the film and a high voltage resistance thereof. In a manufacturing method in which an extruding equipment 10 is charged with a molding material 1 to extrude a film 2 for a film capacitor from a T dice 20, in which the above extruded film 2 for a film capacitor is interposed between plural rolls in a receiving device 30 and cooled and in which the above cooled film 2 for a film capacitor is wound on a winding tube 42 of a winding device 40, 100 parts by mass of a polyetherimide resin is blended with 1 to 10 parts by mass of a fluorocarbon resin to prepare the molding material 1; the above molding material 1 is extruded through a filter 50 having apertures 51 which are 0.5 to 6 times or less as large as an average thickness of the film 2 for a film capacitor, which is provided between the extruding equipment 10 and the T dice 20; and a thickness of the film 2 for a film capacitor is controlled to 10 μm or less.