The invention is directed to a system that can easily generate determination conditions and determine a plurality of similar junk electronic mail pieces based on one determination condition. An electronic mail determination system comprises a junk electronic mail determination processing section (2) for determining whether or not a given electronic mail piece through an input section (1) is junk based on the determination condition stored in a junk electronic mail determination condition storage section (3), an estimated junk electronic mail storage section (6) for storing the electronic mail piece if the electronic mail piece is determined junk by the junk electronic mail determination processing section, and a junk electronic mail exemplification learning section (7) for analyzing content information of the electronic mail piece stored in the storage section (6) for extracting a feature amount to determine that electronic mail is junk and adding the extracted feature amount to the junk electronic mail determination condition storage section as a junk electronic mail determination condition. A keyword vector is used as the determination condition.