To provide a magnet roller and a method for manufacturing the same capable of preventing local reduction of magnetic flux density or poor copy of an image caused by variations of the magnetic flux density in an axial direction and increasing the flexural strength of the magnet roller.

The method comprises the steps of inserting a firs sliding mold 30 into a cylindrical cavity 22 from a left end 26 side, feeding a molten resin magnet material 45 into the cavity 22 from a right end 27 side and pulling the first sliding mold 30 out of the cavity 22 in compliance with the feed injection condition of the resin magnet material 45, filling the whole area of the cavity 22 with the molten resin magnet material 45 to form the resin magnet material 45 into a cylindrical form, applying a gas pressure to an inner circumferential surface 46 of the cylindrical resin magnet material 45, inserting a shaft 14 into a hollow part, inserting the first sliding mold 30 and a second sliding mold 32 into the cavity 22 after the resin magnet material 45 is solidified and then taking out the magnet roller 10 from the cavity 22.