A developing device configured to develop latent images on a surface of an image bearer, the developing device comprising: a developing roller configured to carry developer and to rotate in a predetermined direction of rotation and opposed to or in contact with the image bearer to form a development range, the developing roller including a magnetic field generator including a plurality of magnetic poles (P1 to P5) each having a peak of a normal magnetic force in a respective predetermined region around an entire circumference of the developing roller (13 a) in the predetermined direction of rotation; a cover configured to cover the developing roller downstream from the development range in the predetermined direction of rotation, the cover including a first gap portion (13r2) to form a first gap between the first gap portion (13r2) and the developing roller in a first predetermined range in the predetermined direction of rotation; and a sheet member cantilevered by the cover and configured to contact the developer on the developing roller with a flat face (13s3) of the sheet member while trailing along the predetermined direction of rotation at a position downstream from the development range, the sheet member having a secured end (13s1) supported by the cover and a free end tip (13s2), wherein a portion of the sheet member between the secured end (13s1) and the free end tip (13s2) is opposed to one of the plurality of magnetic poles (P1 to P5); characterised in that: the cover further includes a second gap portion disposed adjacent to and downstream from the first gap portion (13r2) in the predetermined direction of rotation to form a second gap smaller than the first gap, between the second gap portion and the developing roller in a second predetermined range in the predetermined direction of rotation, wherein the second gap portion is arc shaped and concentric with the outer circumferential face of the developing roller, the second gap portion is opposed to another of the plurality of magnetic poles (P1 to P5) different from the one of the plurality of magnetic poles (P1 to P5), and a free end tip (13s2) of the sheet member is disposed away from the second gap portion across a gap in the predetermined direction of rotation. a developing roller configured to carry developer and to rotate in a predetermined direction of rotation and opposed to or in contact with the image bearer to form a development range, the developing roller including a magnetic field generator including a plurality of magnetic poles (P1 to P5) each having a peak of a normal magnetic force in a respective predetermined region around an entire circumference of the developing roller (13 a) in the predetermined direction of rotation; a cover configured to cover the developing roller downstream from the development range in the predetermined direction of rotation, the cover including a first gap portion (13r2) to form a first gap between the first gap portion (13r2) and the developing roller in a first predetermined range in the predetermined direction of rotation; and a sheet member cantilevered by the cover and configured to contact the developer on the developing roller with a flat face (13s3) of the sheet member while trailing along the predetermined direction of rotation at a position downstream from the development range, the sheet member having a secured end (13s1) supported by the cover and a free end tip (13s2), wherein a portion of the sheet member between the secured end (13s1) and the free end tip (13s2) is opposed to one of the plurality of magnetic poles (P1 to P5); characterised in that: the cover further includes a second gap portion disposed adjacent to and downstream from the first gap portion (13r2) in the predetermined direction of rotation to form a second gap smaller than the first gap, between the second gap portion and the developing roller in a second predetermined range in the predetermined direction of rotation, wherein the second gap portion is arc shaped and concentric with the outer circumferential face of the developing roller, the second gap portion is opposed to another of the plurality of magnetic poles (P1 to P5) different from the one of the plurality of magnetic poles (P1 to P5), and a free end tip (13s2) of the sheet member is disposed away from the second gap portion across a gap in the predetermined direction of rotation. the cover further includes a second gap portion disposed adjacent to and downstream from the first gap portion (13r2) in the predetermined direction of rotation to form a second gap smaller than the first gap, between the second gap portion and the developing roller in a second predetermined range in the predetermined direction of rotation, wherein the second gap portion is arc shaped and concentric with the outer circumferential face of the developing roller, the second gap portion is opposed to another of the plurality of magnetic poles (P1 to P5) different from the one of the plurality of magnetic poles (P1 to P5), and a free end tip (13s2) of the sheet member is disposed away from the second gap portion across a gap in the predetermined direction of rotation.