To prevent a reactant gas from flowing into a space defined between targets facing each other in a sputtering apparatus in which targets are arranged opposite to each other.

A direct current reactive sputtering apparatus includes: a sputter source 1 including the targets 5, 6 arranged opposite to each other; and a film deposition chamber 2 that is communicated with the sputter source 1 and stores a substrate W that is an object to be treated. In an opening 3 of the sputter source 1, a constricted part 20 that prevents the reactant gas of the film deposition chamber 2 from intruding into the sputter source 1, is formed. The constricted part 20 is defined by protrusions 22, 24 that are protruded from inner walls 31, 32 facing each other in the opening 3, respectively.