An amorphous carbon film forming apparatus includes a supporting electrode that is connected to ground and supports a substrate, a counter electrode that is disposed so as to face the supporting electrode and has a mixed-gas injection orifice, a chamber containing the supporting electrode and the counter electrode, and a DC pulse generator having a pulse source that applies a DC pulse voltage between the supporting electrode and the counter electrode. An amorphous carbon film is formed by supplying a mixed gas between the supporting electrode and the counter electrode such that the percentage of the acetylene gas relative to the carrier gas is 0.05% by volume or more and 10% by volume or less, and by generating plasma while a DC pulse voltage having a pulse width of 0.1 μsec or more and 5.0 μsec or less is applied to the counter electrode.