A resin filling device for a laminated iron core, the resin filling device being used when a magnet insertion hole provided in the laminated iron core of a rotor for an electric motor is filled with a molten resin for fixing a magnet. The resin filing device configured with a resin feeding mold, an opposing mold, and a pressing mechanism that applies a compression force with the laminated iron core sandwiched between the resin feeding mold and the opposing mold. The resin feeding mold includes one or more discharge outlets arranged so as to face the opening of the magnet insertion hole, and configured to include a diameter reducing part in which an inner diameter is reduced gradually along a discharge direction of the molten resin. A diameter reducing part is arranged inside of the laminated iron core.