Abstract: An aspect of the present invention has a first disk-shaped member coupled to a first rotating shaft to rotate and a first plate-shaped member having a surface perpendicular to a surface of the first disk-shaped member and holding a first magnet. Moreover, a second disk-shaped member provided so as to face the first disk-shaped member and coupled to a second rotating shaft to rotate, and a second plate-shaped member having a surface perpendicular to a surface of the second disk-shaped member and holding a second magnet are provided. A magnetic pole of the first magnet on a side facing the second magnet and a magnetic pole of the second magnet on a side facing the first magnet have the same pole.