The nature of the interaction between Mn atoms which is responsible for the helical magnetic structureand the metamagnetic behavior ofAu2Mnis examined by analyzing the magnetic behavior of Au-Mnsystem in general. From the comparison of the magnetic structure ofAu2Mnand that ofAu4Mn, themagnetic dipole interaction is suggested as one of the possible main weak interactions which connects thesuccessive layers of Mn atoms ofAu2Mn.