A method of forming a diamond-like carbon film, the method comprising: a placement step of placing a metallic film formation target (30, 40), on which a diamond-like carbon film is to be formed, in a flow channel through which film formation gas containing methane gas and argon gas supplied from a gas source is caused to flow; the method being characterized in that it further comprises an impurity removal/film formation step of forming the diamond-like carbon film on a film formation target surface (30f, 40f) of the film formation target (30, 40) by causing the film formation gas from the gas source to flow through the flow channel at a predetermined flow rate during a process of raising the temperature of the film formation target (30, 40) from room temperature to a predetermined temperature to allow the film formation gas to react with impurities in the film formation target surface (30f, 40f) for removal of the impurities from the film formation target surface (30f, 40f) and further to allow the film formation gas to react with a metallic element exposed by the removal of the impurities, wherein the method is carried out in a film formation apparatus comprising the gas source including a methane gas source and an argon gas source; the flow channel provided with a furnace (26, 46); and a controller controlling the gas source and the flow channel, wherein the controller includes a gas controller, which is configured to control the mixing ratio of the methane gas to the argon gas and regulate the flow rate of the film formation gas, and a temperature controller, which is configured to control the temperature of the film formation gas. a placement step of placing a metallic film formation target (30, 40), on which a diamond-like carbon film is to be formed, in a flow channel through which film formation gas containing methane gas and argon gas supplied from a gas source is caused to flow; the method being characterized in that it further comprises an impurity removal/film formation step of forming the diamond-like carbon film on a film formation target surface (30f, 40f) of the film formation target (30, 40) by causing the film formation gas from the gas source to flow through the flow channel at a predetermined flow rate during a process of raising the temperature of the film formation target (30, 40) from room temperature to a predetermined temperature to allow the film formation gas to react with impurities in the film formation target surface (30f, 40f) for removal of the impurities from the film formation target surface (30f, 40f) and further to allow the film formation gas to react with a metallic element exposed by the removal of the impurities, wherein the method is carried out in a film formation apparatus comprising the gas source including a methane gas source and an argon gas source; the flow channel provided with a furnace (26, 46); and a controller controlling the gas source and the flow channel, wherein the controller includes a gas controller, which is configured to control the mixing ratio of the methane gas to the argon gas and regulate the flow rate of the film formation gas, and a temperature controller, which is configured to control the temperature of the film formation gas.