An image forming apparatus includes a developer carrying member to which a developing bias is applied. A frequency f of a developing bias waveform, a developing area S1 which is a time-integrated value of a difference between a voltage value of the developing bias and a solid electrostatic image potential VL in a developing period of the developing bias, a collecting area S2 which is a time-integrated value of a difference between the voltage value of the developing bias and VL in a collecting period of the developing bias, and a developing contrast value Vcon are used for defining a range of a value of the developing bias frequency f, a range of a value of a voltage change rate α at VL during transition of the developing bias voltage value from a developing-side voltage to a collecting-side voltage, and a range of a value represented by the formula: S ⁢ 1 - 1.28 × S ⁢ 2 × f / Vcon × exp - 2.0 × 10 - 5 × f / Hz .