A developing apparatus includes a developer carrying sleeve for carrying a developer to a position opposing an image bearing drum. The sleeve is provided with a plurality of groove portions extending in an axial direction of the sleeve, and a developing bias voltage applying device for applying a developing bias voltage to the sleeve. The bias voltage applying device is capable of outputting, as the bias voltage, a voltage of a waveform having a cyclic period including an AC bias portion having an AC component and a DC component superimposed thereto, and a blank portion following the AC bias portion and consisting of a DC component. A width L (m) of the groove, a peripheral speed Vs (m/s) of the sleeve, and a duration t1 (s) of the blank portion in one cyclic period of the bias voltage satisfy L/Vs