The virus-inactivating effect of calcinated calcium and the like is elucidated, and a novel virus-inactivating agent particularly having a norovirus-inactivating effect is provided. The virus-inactivating agent comprises an aqueous solution or dispersion which is prepared by adding at least one component selected from calcium hydroxide, calcium oxide and calcinated calcium to water. In addition to the above-mentioned components, the virus-inactivating agent may additionally comprise ethanol and a salt of an organic acid.