A method for forming a film on a substrate by continuous vapor deposition, wherein (i) the substrate is introduced into a film-forming apparatus having a plasma-employing roller-type pretreatment device installed in series, the roller-type continuous vapor deposition film-forming apparatus comprising a pressure reduction chamber, conveying means (13, 14a, 14b, 14c, 14d, 15) that conveys the substrate in the pressure reduction chamber, means (35a, 35b, 35c) that isolates the pressure reduction chamber interior into at least a pretreatment compartment and a film formation compartment, a pretreatment roller provided in the pressure reduction chamber for at least plasma treatment of the taken-up substrate, and a plurality of substrate treatment rollers including a film-forming roller for film formation of a vapor deposition film on the substrate pretreated surface, plasma pretreatment means comprising plasma-supply means (22a, 22b) and magnetic field-forming means, the plasma-supply means (22a, 22b) comprising a starting material volatilizing and supply apparatus, and vapor deposition film-forming means for forming a vapor deposition film on the plasma-pretreated substrate surface, wherein the plasma-employing roller-type pretreatment device comprises the pretreatment roller and the plasma pretreatment means, and wherein the plasma-supply means (22a, 22b) and the magnetic field-forming means are arranged on the opposite side of the pretreatment roller facing the pretreatment roller, (ii) plasma pretreatment of the substrate is performed, wherein the supply apparatus supplies a plasma source gas composed of oxygen, nitrogen, carbon dioxide gas, ethylene or a mixture of one or more of these with argon and the plasma pretreatment means (22a, 22b), magnetic field-forming means and the pretreatment roller form a limited and surrounded gap and the plasma is supplied into the limited gap, the gap entrapping the plasma, while it is held with a desired voltage being applied between the plasma pretreatment roller and the plasma-supply means (22a, 22b), and (iii) forming the vapor deposited film. (i) the substrate is introduced into a film-forming apparatus having a plasma-employing roller-type pretreatment device installed in series, the roller-type continuous vapor deposition film-forming apparatus comprising a pressure reduction chamber, conveying means (13, 14a, 14b, 14c, 14d, 15) that conveys the substrate in the pressure reduction chamber, means (35a, 35b, 35c) that isolates the pressure reduction chamber interior into at least a pretreatment compartment and a film formation compartment, a pretreatment roller provided in the pressure reduction chamber for at least plasma treatment of the taken-up substrate, and a plurality of substrate treatment rollers including a film-forming roller for film formation of a vapor deposition film on the substrate pretreated surface, plasma pretreatment means comprising plasma-supply means (22a, 22b) and magnetic field-forming means, the plasma-supply means (22a, 22b) comprising a starting material volatilizing and supply apparatus, and vapor deposition film-forming means for forming a vapor deposition film on the plasma-pretreated substrate surface, wherein the plasma-employing roller-type pretreatment device comprises the pretreatment roller and the plasma pretreatment means, and wherein the plasma-supply means (22a, 22b) and the magnetic field-forming means are arranged on the opposite side of the pretreatment roller facing the pretreatment roller, (ii) plasma pretreatment of the substrate is performed, wherein the supply apparatus supplies a plasma source gas composed of oxygen, nitrogen, carbon dioxide gas, ethylene or a mixture of one or more of these with argon and the plasma pretreatment means (22a, 22b), magnetic field-forming means and the pretreatment roller form a limited and surrounded gap and the plasma is supplied into the limited gap, the gap entrapping the plasma, while it is held with a desired voltage being applied between the plasma pretreatment roller and the plasma-supply means (22a, 22b), and (iii) forming the vapor deposited film.