The influence of an AC electromagnetic field on the interface potentials (zeta potential) of calcium carbonate in an aqueous solution was investigated. By using a suspension of calcium carbonate microparticles in an electrolytic solution, we investigated the changes in the zeta potential of the particles by treating them to a weak AC electromagnetic field at different frequencies; the frequencies ranged from 1 to 10 kHz and the magnetic field intensity did not exceed approximately 150 μT. The method adopted for the measurement of the zeta potential is a simple technique that involves observing migrating particles in a handmade electrophoretic cell under a microscope and calculating the potential from their mobility. Consequently, we found that treatment at a specific frequency drastically changes the zeta potential of the particles in addition to causing an inversion of polarity. From this result, we concluded that the drastic change observed at the solid-liquid interface was due to the AC electromagnetic treatment at a specific frequency (several kilohertz or more). Since the interaction of water, ions, and calcium carbonate with a magnetic field is considerably small, the abovementioned drastic change could be due to an induced electric field accompanying the magnetic field variation. This change is considered to be due to the specific adsorption of anions in the solution on the particle interface.