NOVELTY - A surface treatment layer (101) and gas barrier layer (102) are formed by glow plasma on the web-like base material. A metal roll electrode, and ground electrode arranged in the shape along a metal roll electrode, is provided. One or more type gas chosen from nitrogen, helium and argon between the electrodes is introduced under pressure of 0.5-50 Pa in process space. The plasma surface treatment layer is formed in the base-material surface, and gas barrier layer containing aluminum oxide is formed by dry-coating method on plasma surface treatment layer, to obtain gas-barrier film.    USE - Manufacture of gas-barrier film (claimed) for back sheet of used as packaging field for foodstuff and pharmaceutical, and solar cell.    ADVANTAGE - The gas-barrier film is efficiently manufactured with high productive efficiency, and improved adhesiveness.    DETAILED DESCRIPTION - A surface treatment layer and gas barrier layer are formed by glow plasma on the web-like base material. A metal roll electrode which is a high frequency application electrode in which a base material is driven, and ground electrode arranged in the shape along a metal roll electrode in which magnet of one or more pairs of south-north-pole is installed on the surface which is opposite to the metal roll electrode as counter electrode which opposes the metal roll electrode, is provided. The shortest distance which ties between both electrodes is installed to 50 mm or less by plasma processing apparatus. One or more type gas chosen from nitrogen, helium and argon between the electrodes is introduced under pressure of 0.5-50 Pa in process space. The product of electric power density (W/m2) of opening portion is 50-200 W.second/m2 which is computed from ratio of process portion of electric power (W) and the metal roll supplied into the metal roll electrode, and area (m2) in processing-time (second), when the high frequency voltage is supplied having high frequency of 30 kHz to 30 MHz. The plasma surface treatment layer is formed in the base-material surface which generates a plasma and drive the metal roll electrode top between electrodes. The gas barrier layer containing aluminum oxide is formed by the dry-coating method on the plasma surface treatment layer, to obtain gas-barrier film. An INDEPENDENT CLAIM is included for gas-barrier film.    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional view of gas-barrier film.    Plastic film (100)    Surface treatment layer (101)    Gas barrier layer (102)    Protective layer (103)