a thin film depositing method comprising placing a substrate in a heating chamber ; allowing a first gas to flow inside the heating chamber to heat the substrate through heat exchange with the first gas ; moving the substrate to a deposition chamber , evacuating the deposition chamber , and then supplying a second gas into the deposition chamber ; and causing an electrical discharge in the second gas such that the second gas decomposes into decomposition components and the decomposition components adhere to a substrate surface to deposit a film thereon , wherein the first gas is a gas from which moisture and organic substances have been removed . the time required for depositing thin films is reduced thereby improving the throughput , increases in apparatus costs are suppressed , and a thin film having good properties is obtained . a thin film depositing apparatus is also provided .