A DLC film mass-producing apparatus 10 includes a chamber 12 connected to ground. In the chamber 12, a plurality of plate-shaped substrates 60 are disposed in parallel at regular intervals, without disposing a counter electrode that faces each of the plate-shaped substrates 60. Sputtering cleaning is then conducted by plasma discharge and an underlying contact layer is formed on each of the plate-shaped substrates 60. Subsequently, a DLC film is produced on each of the plate-shaped substrates 60 by injecting a carbon source gas into the chamber 12 such that the internal pressure of the chamber 12 reaches 0.1 to 10 Pa and applying a negative DC pulse voltage having a pulse half width of 0.1 to 3 μsec to each of the plate-shaped substrates 60 to generate plasma.