A magneto generator can increase a suppression force to suppress permanent magnets from being moved to an opening side of a flywheel with easy construction and at low cost. In this magnet generator, the flywheel has a groove formed on its inner peripheral wall surface at an opening side thereof, and a magnet positioning member has a magnet coming-off preventing member formed at the opening side of the flywheel so as to cover end faces of the permanent magnets, with a protrusion being formed on the magnet coming-off preventing member so as to engage the groove in the flywheel. The protrusion is in engagement with the groove whereby the movement in an axial direction of the permanent magnets can be suppressed.