A magnet splitting device (100, 200, 300) for splitting a pre-split magnet (10, 30) with a splitting groove (11, 31) along the splitting groove, comprising: a one-side holder (110, 310) for holding the pre-split magnet on one side of the splitting groove and an other-side holder (130, 230, 330) for holding the pre-split magnet on the other side, the one-side holder and the other-side holder being configured to split apart the pre-split magnet along the splitting groove as a starting point by relative movement of the other-side holder relative to the one-side holder in such a manner as to widen an opening (11i, 31i) of the splitting groove more than a bottom part (11j, 31j) of the groove; and an actuating unit (150, 250) configured to generate the relative movement of the other-side holder, characterized in that the one-side holder and the other-side holder are configured to hold a plurality of pre-split magnets simultaneously and to split apart these pre-split magnets all at once, the other-side holder includes a plurality of other-side independent holding parts (131, 231, 331) configured to respectively hold the other sides of the pre-split magnets independently and undergo the relative movement independently from each other, and in that the actuating unit includes: a plurality of independent actuating parts (151, 251) configured to generate the relative movement independently in the respective other-side independent holding parts; and a simultaneous operating part (153, 253) configured to operate the independent actuating parts simultaneously. a one-side holder (110, 310) for holding the pre-split magnet on one side of the splitting groove and an other-side holder (130, 230, 330) for holding the pre-split magnet on the other side, the one-side holder and the other-side holder being configured to split apart the pre-split magnet along the splitting groove as a starting point by relative movement of the other-side holder relative to the one-side holder in such a manner as to widen an opening (11i, 31i) of the splitting groove more than a bottom part (11j, 31j) of the groove; and an actuating unit (150, 250) configured to generate the relative movement of the other-side holder, characterized in that the one-side holder and the other-side holder are configured to hold a plurality of pre-split magnets simultaneously and to split apart these pre-split magnets all at once, the other-side holder includes a plurality of other-side independent holding parts (131, 231, 331) configured to respectively hold the other sides of the pre-split magnets independently and undergo the relative movement independently from each other, and in that the actuating unit includes: a plurality of independent actuating parts (151, 251) configured to generate the relative movement independently in the respective other-side independent holding parts; and a simultaneous operating part (153, 253) configured to operate the independent actuating parts simultaneously. a plurality of independent actuating parts (151, 251) configured to generate the relative movement independently in the respective other-side independent holding parts; and a simultaneous operating part (153, 253) configured to operate the independent actuating parts simultaneously.