A magnet splitting device includes a one-side holder for holding a plurality of pre-split magnets on one sides of respective splitting grooves, an other-side holder for holding the magnets on the other sides, and an actuating unit for causing relative movement of the other-side holder to split the magnets all at once. The other-side holder includes a plurality of other-side independent holding parts for holding the magnets independently. The actuating unit includes a plurality of independent actuating parts for moving the other-side independent holding parts independently and a simultaneous operating part for simultaneously operating the holding parts.