A substrate processing apparatus forms a thin film of high-dielectric or ferroelectric such as barium/strontium titanates, or a copper film for wiring on a substrate, and has a gas ejection head for individually introducing at least two gases including a material gas and ejecting the gases toward a substrate to be processed. The gas ejection head has at least two gas passageways for individually introducing the two gases, and at least two temperature control devices for individually controlling temperatures of the gases flowing through the gas passageways.