To provide a vacuum film-forming apparatus which can form a film in a vacuum by continuously supplying a sheet substrate into a vacuum chamber, further can install a pay-out reel and a take-up reel in an ambient pressure side (outside), and can be continuously operated without breaking the vacuum.

This vacuum film-forming apparatus includes: the vacuum chamber 3 in which the film is formed on the continuous strip-shaped sheet substrate 1 that is continuously supplied into the chamber, under a condition of a high vacuum P7; the pay-out reel R1 which is installed in an ambient pressure P0 side that is positioned outside the vacuum chamber 3, and pays out the sheet substrate 1; a stepwise pressure-reducing means 4 which is installed between the pay-out reel R1 and an entrance side of the vacuum chamber 3, and gradually reduces the pressure through a plurality of stages from ambient pressure P0 to the high vacuum P7; the take-up reel R2 which is installed in an ambient pressure P0 side that is positioned outside the vacuum chamber 3, and winds up the sheet substrate 1 after the film has been formed; and a stepwise pressure-restoring means 5 which is installed between the outlet side of the vacuum chamber 3 and the take-up reel R2, and gradually restores the pressure through a plurality of stages from the high vacuum P7 to the ambient pressure P0.