A manufacturing method for an electric motor rotor includes: a stacking process in which a plurality of iron core pieces are stacked to form a laminated iron core; a magnet insertion process in which a permanent magnet is inserted into a magnet insertion hole provided in the laminated iron core; a resin filling process in which the laminated iron core is heated to fill the magnet insertion hole with a molten resin for magnet fixation; and a rotary shaft assembly process in which a rotary shaft is warm-fitted into a rotary shaft insertion hole of the laminated iron core utilizing residual heat from the heating of the laminated iron core 10 in the resin filling process.