An antiviral agent is provided which is effective in treating coronaviruses and can be formed into various products whose efficacy sustainability is promising. In particular, the present invention provides an antiviral agent which is effective in treating a coronavirus, comprising a silver ion carrier; a product capable of inactivating a coronavirus, comprising the same; and a method of inactivating a coronavirus. The silver ion carrier is at least one selected from a compound represented by the following formula (1), potassium titanate, potassium uranate, potassium vanadate, potassium niobate, sodium tangustate, magnesium molybdate, calcium pentaborate, aluminosilicate, aluminum phosphate, nickel hexacyanoferrate, sepiolite, montmorillonite, silica gel, zeolite, .beta.-alumina, titanium oxide hydrate, hydroxyapatite and a glassy carrier. Ag.sub.aA.sub.bM2.sub.c(PO.sub.4).sub.d.nH.sub.2O (1)