Abstract: This method for manufacturing a rotor core includes an injection step of injecting a molten resin material into a magnet housing portion of a laminated core heated to a third temperature by a preheating step. The injection step is a step of injecting the resin material into the magnet housing portion while releasing to the outside of the magnet housing portion a volatile organic compound volatilized by heating the resin material by bringing the resin material into contact with the laminated core heated to the third temperature.

Abstract: A rotor core includes a thermosetting resin material disposed in a magnet housing portion to fix a permanent magnet in the magnet housing portion. The resin material has a coefficient of linear expansion that is equal to or less than the coefficient of linear expansion of electromagnetic steel sheets.

Abstract: An object of the present invention is to provide a crystalline radically polymerizable composition for fixing a magnet of a rotating electric machine rotor core, which is excellent in handleability around room temperature, excellent in fluidity from the injection step to the curing step, and excellent in strength of the cured product. A crystalline radical polymerizable composition for fixing a magnet of a rotating electric machine rotor core of the present invention is characterized by fixing the magnet inserted in a magnet accommodating portion provided in a rotor core of a rotating electric machine formed of a laminated steel sheet and the laminated steel sheet, wherein the crystalline radical polymerizable composition contains at least a crystalline radical polymerizable compound A, an inorganic filler B, a silane coupling agent C, and a radical polymerization initiator D, wherein the crystalline radical polymerizable compound A is solid at 23° C.