A magnetizing device for a magnetic encoder operable to magnetize an annular magnetic body that integrally has a plurality of unmagnetized annular magnetic encoder tracks (3, 4) arranged so as to adjoin each other, by causing the annular magnetic body to rotate to magnetize circumferential portions of the annular magnetic body one at a time, thereby producing a magnetic encoder with the magnetic encoder tracks (3, 4), which have respective magnetic patterns formed thereon that are different from each other, the magnetizing device comprising: a magnetization yoke for magnetizing a magnetic encoder track (3, 4) of the magnetic encoder arranged in a defined location and position relative to the magnetization heads, wherein the magnetization yoke includes a pair of magnetization heads which are magnetically confronting each other through a magnetic gap; an excitation coil wound around the magnetization yoke: a magnetization power supply for supplying a magnetizing current to the excitation coil to generate magnetic flux between the pair of magnetization heads; two magnetic shields provided on the magnetization yoke, the two magnetic shields being disposed on opposite sides of one of the magnetization heads along a direction in which the magnetic encoder tracks (3, 4) are arranged such that the one of the magnetization heads is interposed between the two magnetic shields, each of the two magnetic shields being spaced apart from one of the magnetization heads with a gap being formed therebetween along a direction in which the plurality of the magnetic encoder tracks (3, 4) are arranged, and being configured to block a flow of magnetic flux that is present outside a defined extension of a flow of the magnetic flux between the magnetization heads, characterized in that each of the two magnetic shields being of such a geometry that a thickness thereof progressively decreases towards the one of the magnetization heads. a magnetization yoke for magnetizing a magnetic encoder track (3, 4) of the magnetic encoder arranged in a defined location and position relative to the magnetization heads, wherein the magnetization yoke includes a pair of magnetization heads which are magnetically confronting each other through a magnetic gap; an excitation coil wound around the magnetization yoke: a magnetization power supply for supplying a magnetizing current to the excitation coil to generate magnetic flux between the pair of magnetization heads; two magnetic shields provided on the magnetization yoke, the two magnetic shields being disposed on opposite sides of one of the magnetization heads along a direction in which the magnetic encoder tracks (3, 4) are arranged such that the one of the magnetization heads is interposed between the two magnetic shields, each of the two magnetic shields being spaced apart from one of the magnetization heads with a gap being formed therebetween along a direction in which the plurality of the magnetic encoder tracks (3, 4) are arranged, and being configured to block a flow of magnetic flux that is present outside a defined extension of a flow of the magnetic flux between the magnetization heads, characterized in that each of the two magnetic shields being of such a geometry that a thickness thereof progressively decreases towards the one of the magnetization heads.