A developing apparatus includes a sleeve for carrying a developer including toner and magnetic carrier, the sleeve having a plurality of grooves extending in a longitudinal direction; a magnet provided inside the sleeve, a non-magnetic regulating member, provided spaced from the sleeve, wherein an amount M/S (mg/mm2) of the developer carried on a unit area of the sleeve after passing by the regulating member, a gap SB (mm) between a free end of the regulating member and the sleeve, a density G (mg/mm3) of the developer, and a groove ratio α which is a ratio of the grooves in the surface of the sleeve satisfy, 0.1≤M/S (mg/mm2)≤0.5, 0.2≤SB (mm), and m/S (mg/mm2)×¼≤α×{SB(mm)+D(mm)}×G(mg/mm3)