Abstract: An airtight magnetic seal (1) that uses the repulsive property inherent in magnetic bodies of the same polarity to keep seal components in permanent contact. The seal is provided with a magnetic device capable of hermetically sealing the inside of the bearing casing. In addition it is of a reduced external size. A set of components, such as: head, primary seal, magnets, housing, baffles, and O-rings, arranged in such a way that the peculiar configuration and dispositions of the construction allow the attainment of a total thickness, after mounting, which is thinner than the seals currently in existence.