We measured the local magnetic moments at grain boundaries in Fe–Si and Fe–Sn alloys by electron energy loss spectroscopy with a transmission electron microscope and evaluated the relation between the grain boundary magnetism and grain boundary segregation in Fe–Si and Fe–Sn alloys. We found that the local magnetic moments at the random boundaries in these alloys were remarkably reduced in comparison with those in pure Fe, whereas there was no considerable change at the Σ5 grain boundary and low-angle boundary. The variation of the local magnetic moments at impurity-segregated grain boundaries was explained by the competition between magnetovolume effect and hybridizations of electrons. It was found that the grain boundary character remarkably affects this hybridization. The decrease in the magnetic moments at random grain boundaries was more pronounced in the Fe–Sn alloy than in the Fe–Si alloy.