A resin-filled carrier for an electrophotographic developer obtained by filling resin into voids of a porous ferrite core material, wherein the porous ferrite core material has a pore volume of 0.04 to 0.16 mL/g and a peak pore size of 0.9 to 2.0 .mu.m, and wherein microparticles are included in the resin to be filled, and an electrophotographic developer using this resin-filled carrier.