A method for manufacturing carrier core particles for electrophotographic developer including a slurrying step (A) of making an iron-containing raw material and a strontium-containing raw material into slurry, a granulation step (B) of granulating the slurry mixture obtained in the slurrying step, and a firing step (C) of firing a powdery material, which is obtained by granulating the slurry mixture in the granulation step, at a predetermined temperature to form a magnetic phase. The slurrying step makes the iron-containing raw material into the slurry containing the iron-containing raw material having a volume diameter D50 of 1.0 to 4.0 μm and a volume diameter D90 of 2.5 to 7.0 μm, and makes the strontium-containing raw material into the slurry so that the carrier core particles for electrophotographic developer contain 0