To provide a film deposition system and a film deposition method by which exact film deposition rate of a film deposited on an object to be treated can be detected and the film thickness of the film deposited on a substrate can be uniformized based on a detected potential.

The film deposition system is equipped with: an aerosol forming vessel 100 for forming aerosol; a spray nozzle 10 for spraying the aerosol formed in the aerosol forming vessel 100 as an aerosol flow; a holder 12 for holding the object 13 to be treated so that the aerosol flow is sprayed onto the object 13 to be treated; a driving device 50 which has a conductor 15 onto one surface of which the aerosol flow is sprayed, and moves the conductor 15 relatively to the spray nozzle 10 so that the aerosol flow is sprayed successively onto an area, where the aerosol flow is not sprayed, of the one surface of the conductor 15; and a potential detection means 70 for detecting the potential of the conductor 15.