PROBLEM TO BE SOLVED: To provide an antiviral agent containing an active ingredient having excellent activity for deactivating non-envelope virus, and highly safe to a human body, and usable for disinfection, prevention of infection and the like of these viruses in various forms.SOLUTION: The antiviral agent includes an extract of plants belonging to genus Chaenomeles containing a tannin-like substance as an active ingredient. The extract is preferably obtained from a fruit of Chaenomeles sinensis.