ClamXav

Free GUI front end to the ClamAV opensource virus checker. Update the virus definitions. Point it to a file or folder and scan. Other features include logging results to a file, placing infected files into quarantine, monitoring folders for changes to their contents and a Finder Contextual Menu Item.

Mac用のアンチウイルスソフト、VersionTrackerにしっかりありました。Freeだし、これにしよう。