The present invention provides a magnesium-based ferrite having a high dielectric breakdown voltage and a saturation magnetization suitable for electrophotographic development, a carrier containing the ferrite, and an electrophotographic developer containing the carrier. The magnesium-based ferrite material of the present invention contains Li, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ti, Zr, Hf, V, Nb, Ta, Al, Ga, Si, Ge, P, Sb, Bi or combinations thereof. The saturation magnetization of the magnesium-based ferrite material is 30 to 80 emu/g, and the dielectric breakdown voltage is 1.5 to 5.0 kV. The magnesium-based ferrite material achieves high image quality and meets environmental regulations.