The present invention provides: (1) antiviral agents that act by reducing or inhibiting the activity of SR proteins, more specifically, (i) antiviral agents that act by enhancing dephosphorylation of SR proteins, and (ii) antiviral agents that act by inhibiting proteins that phosphorylate SR proteins; (2) antiviral agents that act by inhibiting the expression of SR proteins, and (3) antiviral agents that act by activating proteins that antagonize SR proteins. The present invention also provides compounds that inhibit SRPKs, which phosphorylate SR proteins. Such compounds inhibit the activity of SR proteins and have antiviral activities. Various new viruses including SARS have emerged, and thus the present invention provides long-lasting broad-spectrum antiviral agents applicable to new viruses.