Carrier core material for electrophotographic developer, and manufacturing method of the same, carrier for electrophotographic developer, and electrophotographic developer

A method for manufacturing a carrier core material for electrophotographic developer comprising the steps of:

• preparing Fe raw material powders, Mn raw material powders, and Mg raw material powders, then dividing the whole volume of particles into each particle size, and obtaining a cumulative curve of a volume in each particle size from the side of a small particle side, with the whole volume of the particles set as 100%, and making the particles finer so that a value of D90 is set to be 1.0 μm or less when the particle size at cumulative curve of 90% is expressed by D90;
• turning the obtained fine particles into slurry by stirring the powders in a medium solution;
• obtaining granulated powders by drying and granulating the obtained slurry;
• obtaining a sintered material having a magnetic phase by sintering the obtained granulated powders;
• and
• turning the obtained sintered material into powders by applying pulverization process thereto, to have a prescribed particle size distribution thereafter.