To provide a developing roller which makes it possible to sufficiently prevent toner leakage, with the driving torque of the developing roller being scarcely increased, and a mono-component developing apparatus having such a developing roller. A developing roller for a mono-component developing apparatus, which transports toner supported on an outer circumferential face of a center portion 12 toward a developing area by rotating while frictionally sliding on a sealing member on each of two end portions 11a, 11b, comprising: surface processing areas 13 having a spiral shape, placed on each of outer circumferential faces of the two end portions, wherein an angle .theta., made by a spiral direction y of each surface processing area and the rotation direction x, is allowed to have an acute angle, and a mono-component developing apparatus having such a developing roller.