Abstract: A method includes introducing an organic metal gas containing hydrogen into a deposition vessel to cause a component of the organic metal containing hydrogen to be adsorbed on a substrate; introducing an oxidizing gas or a nitriding gas into the vessel, generating plasma with the oxidizing gas or the nitriding gas by a plasma source, and oxidizing or nitriding the component; detecting emission intensity of a wavelength of light through an observation window in the vessel, the light being emitted, by generating the plasma, from an excited hydrogen radical resulting from the hydrogen separated from the organic metal above the substrate when the organic metal reacts with the oxidizing gas or the nitriding gas to form an oxidized metal or a nitride metal on the substrate; and stopping the generation of the plasma when a value of the detected emission intensity becomes a first predetermined value or less.