A magnetizing device includes a magnetization yoke including a pair of magnetization heads confronting each other through a magnetic gap, an excitation coil wound around the magnetization yoke, and a magnetization power supply that supplies a magnetizing current to the excitation coil to generate magnetic flux between the magnetization heads. A magnetic shield is provided on the magnetization yoke. The magnetic shield is spaced apart from one of the magnetization heads with a gap being formed therebetween along a direction in which the plurality of magnetic encoder tracks are arranged. The magnetic shield blocks a flow of magnetic flux that is present outside a defined extension of a flow of the magnetic flux between the pair of magnetization heads. The magnetic shield is of such a geometry that a thickness thereof progressively decreases towards the one of the magnetization heads.