There is provided a method for forming a Ge—Sb—Te film having a composition of Ge2Sb2Te5 on a substrate by a CVD method using a gaseous Ge source material, a gaseous Sb source material and a gaseous Te source material. The method includes loading the substrate within a processing chamber (Process 1); performing a first stage film forming process on the substrate by supplying the gaseous Ge source material and the gaseous Sb source material (Process 2); and performing a second stage film forming process on a film obtained through the first stage film forming process by supplying the gaseous Sb source material and the gaseous Te source material (Process 3). The Ge—Sb—Te film is formed by the film obtained through Process 2 and by a film obtained through Process 3.