A processing system for forming a film on a target object having thereon an insulating layer that is made of a low-k film and having a recess is provided. The processing system comprises: a processing apparatus configured to form a first-metal-containing film containing a first metal on a surface of the target object; a processing apparatus configured to form a second-metal-containing film containing Mn as a second metal having a barrier property against a filling metal to be filled in the recess; a processing apparatus configured to form a thin film made of a third metal as the filling metal to be filled; a common transfer chamber connected with each of the processing apparatuses; a transfer unit for transferring the target object into each of the processing apparatuses; and a system controller that controls the whole processing system so as to perform a film forming method.