An object of the present invention is to provide a carrier containing core material particles having magnetism and a coating layer on the surfaces of the core material particles, wherein the core material particles have a magnetization at a magnetic field of 1,000 Oersted of 40 emu/g to 100 emu/g, and the carrier has a weight average particle diameter of 20 .mu.m to 45 .mu.m, a resistance (LogR) of 11 .OMEGA.cm to 17 .OMEGA.cm and a relaxation time .tau. of 150 seconds to 800 seconds.