A magnetoelectric generator includes a bowl-like flywheel (3) having a bottom portion (6) formed with ventilation holes (20), a plurality of permanent magnets (7) secured to an inner circumferential surface of the flywheel (3), a stator core (10) disposed within the flywheel (3) and having peripheral side surfaces facing the permanent magnets (7), and a coil assembly (11) implemented by winding an electric conductor on the core (10). Electricity is induced in the coil assembly (11) by AC magnetic field produced by rotating the flywheel (3). A peripheral edge portion of each ventilation hole (20) is formed with a projecting portion (21) by plastic deformation, which protrudes toward the coil assembly (11) for producing turbulent air flows internally of the flywheel (3) upon rotation of the flywheel (3).