The present invention is a method of manufacturing a semiconductor device comprising: forming a recess in an interlayer insulating film formed on a substrate surface, the recess being configured to be embedded with an upper conductive channel mainly made of copper to be electrically connected to a lower conductive channel; supplying a gas containing an organic compound of manganese, and forming a barrier layer made of a compound of manganese for preventing diffusion of copper to the interlayer insulating film, such that the barrier layer covers an exposed surface of the interlayer insulating film; after the formation of the barrier layer, supplying organic acid to the barrier layer in order to increase a ratio of manganese in the compound of manganese forming the barrier layer; after the supply of the organic acid, forming a seed layer mainly made of copper on a surface of the barrier layer; after the formation of the seed-layer, heating the substrate in order to separate out manganese from on the surface of the barrier layer or from in the barrier layer onto a surface of the seed layer; supplying a cleaning liquid to the seed layer in order to remove the manganese separated out on the surface of the seed layer by the heating; and after the supply of the cleaning liquid, forming the upper conductive channel mainly made of copper in the recess.