Abstract: A magnet assembly used as a magnetism generating source for attaching an article to a magnetic substance or for magnetically retaining a magnetic member. The magnet assembly consists of a cylindrical casing open at least at one end, a core disposed within the casing at a spacing from an inner wall thereof, with one end of the core aligned with the open end face of the casing, and a permanent magnet disposed between the core and the inner peripheral surface of the casing. The permanent magnet has one magnetic pole on an outer surface thereof opposing the inner peripheral surface of the casing, and the other magnetic pole opposite the magnetic pole on an inner surface thereof opposing the outer peripheral surface of the core, so that the open end face of the casing and the end face of the core serve as a magnetic attraction surface.