In one embodiment, a substrate treatment apparatus includes cleaning and rinse modules configured to clean and rinse a surface of a substrate provided with a pattern, and a solidifying agent containing liquid supplying module configured to supply a solidifying agent containing liquid that contains a solidifying agent to the cleaned and rinsed surface of the substrate. The apparatus further includes a precipitation module configured to precipitate the solidifying agent as solid on the surface of the substrate, and a decomposition module configured to decompose and gasify the solid to remove the solid from the surface of the substrate. The solidifying agent contains an ammonium salt, and the ammonium salt contains an ammonium ion or an ion having a structure in which at least one of four hydrogen atoms of an ammonium ion is substituted with another atom or atom group.