An ammonia-containing liquid or an ammonia-containing gas is made to contact a porous coordination polymer in which a metal ion and an organic ligand coordinately bonded, ammonia is adsorbed to the porous coordination polymer, and the ammonia is desorbed from the ammonia-adsorbed porous coordination polymer to recover the ammonia. The porous coordination polymer that contacts the ammonia-containing liquid preferably has a water-soluble solvent adhered thereto. The ammonia-containing gas is preferably adjusted such that water is contained at an amount of 106 parts by mass or more when the ammonia content is 100 parts by mass.