Provided is a vessel comprising: a vessel body; an ammonia presence part, which is provided to the vessel body and in which ammonia is present; a gas pressure-feeding unit, which is provided to the vessel body and which pressure-feeds a gas that is non-reactive with respect to the ammonia; a dehumidification unit that dehumidifies the gas being pressure-fed by the gas pressure-feeding unit; and a vent post that discharges the ammonia in the ammonia presence part, together with the gas that has passed through the dehumidification unit, to the atmosphere.