A developing device, comprising: a case for housing a developer; a magnetic roller arranged in the case, including a rotary shaft and configured to magnetically carry the developer on a circumferential surface by rotating about the rotary shaft; an agitating member arranged to face the magnetic roller in the case, including a shaft center and a screw forming portion arranged around the shaft center and configured to agitate and convey the developer while rotating; a layer thickness restricting member arranged to face the magnetic roller and configured to restrict the layer thickness of the developer supplied from the agitating member to the magnetic roller to a predetermined thickness; a plurality of projection members (901, 914) arranged along a rotation axis direction of the magnetic roller to face the circumferential surface of the magnetic roller at a side upstream of the layer thickness restricting member in a rotating direction of the magnetic roller and configured to come into contact with the developer carried on the magnetic roller; and a base portion for supporting the plurality of projection members; wherein: the plurality of projection members are a plurality of elongated projections arranged adjacent to each other along the rotation axis direction of the magnetic roller and groove portions of a predetermined width are formed between adjacent elongated projections, the plurality of elongated projections projecting from the base portion and extending in a first direction at a predetermined angle to a line perpendicular to the rotation axis direction of the magnetic roller, such that a first inclination of a projected shape of a trace of a screw outer rim of the screw forming portion on the circumferential surface of the magnetic roller when the magnetic roller and the agitating member rotate relative to each other and a second inclination of projected shapes of the inclined elongated projections on the circumferential surface of the magnetic roller at a facing position of the magnetic roller and the elongated projections, intersect, wherein the developer in contact with the elongated projections enters the groove portions, is guided to guiding walls of the elongated projections and conveyed in the first direction. a case for housing a developer; a magnetic roller arranged in the case, including a rotary shaft and configured to magnetically carry the developer on a circumferential surface by rotating about the rotary shaft; an agitating member arranged to face the magnetic roller in the case, including a shaft center and a screw forming portion arranged around the shaft center and configured to agitate and convey the developer while rotating; a layer thickness restricting member arranged to face the magnetic roller and configured to restrict the layer thickness of the developer supplied from the agitating member to the magnetic roller to a predetermined thickness; a plurality of projection members (901, 914) arranged along a rotation axis direction of the magnetic roller to face the circumferential surface of the magnetic roller at a side upstream of the layer thickness restricting member in a rotating direction of the magnetic roller and configured to come into contact with the developer carried on the magnetic roller; and a base portion for supporting the plurality of projection members; the plurality of projection members are a plurality of elongated projections arranged adjacent to each other along the rotation axis direction of the magnetic roller and groove portions of a predetermined width are formed between adjacent elongated projections, the plurality of elongated projections projecting from the base portion and extending in a first direction at a predetermined angle to a line perpendicular to the rotation axis direction of the magnetic roller, such that a first inclination of a projected shape of a trace of a screw outer rim of the screw forming portion on the circumferential surface of the magnetic roller when the magnetic roller and the agitating member rotate relative to each other and a second inclination of projected shapes of the inclined elongated projections on the circumferential surface of the magnetic roller at a facing position of the magnetic roller and the elongated projections, intersect, wherein the developer in contact with the elongated projections enters the groove portions, is guided to guiding walls of the elongated projections and conveyed in the first direction.