Provided is an air purifier capable of removing viruses even when pressure loss is reduced due to the gaps between fibers of a filter being made larger than the sizes of the viruses.　The air purifier for removing viruses is capable of collecting small viruses, and comprises: a filter having a mesh with voids larger than the sizes of the viruses; an anionic surfactant adhered to a surface of the filter; and an air blower that produces a flow that causes air containing a virus so to pass through the filter.