Novel antiviral means is disclosed. The antiviral agent of the present invention comprises as an effective ingredient particles having a particle diameter of not more than 5 µm, wherein said particles are polymer particles whose repeat unit comprises a structure represented by a particular general formula, and wherein said particles do not contain an antiviral active component. The polymer particles are preferably cyanoacrylate polymer particles. The antiviral agent of the present invention shows adhesiveness to the surface (especially envelope) of virus particles, and destroys a normal virus particle structure to reduce or eliminate infectivity of the virus particles. Sanitary articles such as masks comprising the antiviral agent of the present invention can exert an excellent effect on prevention of infection with viruses such as influenza virus that occurs through droplet infection or airborne infection.
