A method for manufacturing carrier core particles for electrophotographic developer that include manganese, magnesium, and iron as a core composition. The method includes a granulation step (A) of granulating a mixture of raw materials containing manganese, magnesium, and iron with a reducing agent added at a ratio of 0.10% to 1.00% by mass to a total mass of the raw materials containing manganese, magnesium, and iron, and a firing step of firing the granular material granulated in the granulation step. The firing step includes a first heating step (C) of applying heat at a constant temperature ranging from 500° C. to 800° C. in an atmosphere with an oxygen concentration of 1000 ppm to 15000 ppm for a predetermined period of time and a second heating step (D) of applying heat at a temperature higher than 800° C. for a predetermined period of time after the first heating step.