To provide a magnetizing device for a magnetic encoder that can magnetize double rows of adjoiningly arranged magnetic encoder tracks with high efficiency without affecting the adjacent magnetic encoder track and exclude needless steps, and a compact double-row magnetic encoder using this magnetization.

A magnetizing device 1 magnetizes an annular magnetic member 2 which integrally has double-row annular non-magnetized magnetic encoder tracks 3, 4 which are arranged adjoiningly while rotating the magnetic member 2, thereby obtaining a magnetic encoder. The magnetizing device 1 has a magnetizing yoke 6 having a pair of opposite end portions 6a, 6a confronting each other through a magnetic gap, an exciting coil 7 wound around the magnetizing yoke 6, a magnetizing power supply 8 for supplying magnetizing current to the exciting coil 7 to pass magnetic flux between the opposite end portions 6a, 6a, and a magnetic shield member 9 which is provided to the magnetizing yoke 6 to intercept flow of magnetic flux to the magnetic encoder track of the other row than a magnetization target row.