A magnetic recording medium comprising a plastic base and a magnetic layer formed thereon by applying a dispersion of a ferromagnetic powder in a resin binder, the magnetic layer containing the ferromagnetic powder which has a BET specific surface area of at least 35 m.sup.2 /g and .alpha.-Al2O3 particles having a particle size not exceeding one half the mean particle diameter of the ferromagnetic powder and less than 0.1 .mu.m in diameter, the .alpha.-Al2O3 particles being added in an amount greater than 5% but less than 15% by weight on the basis of the weight of the ferromagnetic powder. The magnetic powder is a metallic magnetic powder containing iron as the major constituent. The .alpha.-Al2O3 particles are cube-shaped.