Magnetite particles of the present invention have an average particle diameter of 0.05 to 0.50 .mu.m, each of the magnetite particles having a plurality of mountain-shaped protrusions with unsharpened crests on a surface of each magnetite particle, and the number of the mountain-shaped protrusions formed on the surface of each magnetite particle being in the range of 2 to 30 when viewed in projected plan; magnetic iron oxide particles for magnetic toner comprising not less than 60%, in particle number, of the said magnetite particles; and a magnetic toner comprising the said magnetic iron oxide particles and a binder resin. The magnetite particles of the present invention are free from the falling-off from toner particles. The toner particles of the present invention shows a good fluidity and produces visual images having a higher definition upon development of electrostatic latent images.