In a method of developing an electrostatic latent image formed on an image bearing member, wherein a developer carrying member carrying a layer of a developer is faced to the image bearing member and is supplied with an oscillating bias voltage to form an oscillating electric field in a developing zone, the improvement residing in: that a maximum Vu1max of a potential difference Vu1 between an image portion potential of the latent image and a potential of the developer carrying member in a transfer phase of the oscillating electric field, is larger than a maximum Vr1max of a potential difference Vr1 therebetween in a back-transfer phase thereof; that a maximum Vu2max of a potential difference Vu2 between a non-image portion potential of the latent image and a potential of the developer carrying member in the transfer phase of the oscillating electric field, is not less than a maximum Vr2max of a potential Vr2 therebetween in the back-transfer phase thereof; that integration Iu2, with time, of the potential difference Vu2 is not more than integration Ir2, with time, of the potential difference Vr2.