The effects of magnetic exposure on several kinds of alkylammonium chloride solutions were investigated using interfacial tension measurements at the mercury/solution interface. The comparison between the electrocapillary curves of magnetized and nonmagnetized solutions revealed that magnetic exposure induced an increase in interfacial tension, and that such an effect was remarkable at around the potential of zero charge. The appearance of the magnetic effect depended on the specific adsorbability of alkylammonium cations, which in turn depended on the kind of cations, The interfacial tension change induced by magnetic exposure quantitatively correlated with the specific adsorbability of the cations. These results indicated that the magnetism induced an effect on the solution of alkylammonium cations having higher specific adsorbabilities.