Magnetizers/demagnetizers are a general term for an energy supply device that magnetizes a permanent magnet to create a high magnetic field, or a machine that extracts magnetism from a magnetized magnetic material. Used for magnetizing and demagnetizing work tools such as drills and end mills, blades, and centering bars. Among them, there are demagnetizers that have a high heat dissipation effect and can be continuously energized and ones that exhibit a high demagnetizing effect even for those that are difficult to demagnetize such as special steel. The types of magnetizers/demagnetizers include a pen type for use in narrow spaces and local areas such as punched parts of press dies and blades attached to machine tools, a table type used for removing residual magnetism of large workpieces, and more. There is also a combined type of a magnetizer and a demagnetizer. The feature is that it can magnetize and demagnetize simply by pressing a button or rubbing against it.