A deposition method for embedding a SiN film in a recessed pattern formed on a surface of a substrate includes: (a) activating and supplying a first process gas containing NH3 to the surface of the substrate and causing NHx groups to adsorb on the surface of the substrate, where x is 1 or 2; (b) supplying a silicon-containing gas to the surface of the substrate on which the NHx groups are adsorbed and causing the silicon-containing gas to adsorb on the NHx groups; and (c) activating and supplying a second process gas containing N2 to the surface of the substrate on which the NHx groups are adsorbed and partly replacing the NHx groups with N groups, wherein (a) and (b) are repeated, and (c) is performed every time (a) and (b) are repeated a predetermined number of times.