The present invention is directed to an extrace of Psilotum spp., as a skin whitening agent. Whitening agents according to the invention exhibit superior effects, for example, by lightening and whitening skin pigmentation, lightening and whitening aging spots, freckles, chloasma, or the like after sunburn. The Psilotum spp. extract of the invention has a superior free radical scavenging ability permitting the extract to control skin aging and skin diseases caused by active oxygen (free radicals), while having a high level of safety.