A developing device includes a developing container for accommodating a magnetic developer containing magnetic toner. First and second developer carrying members carry the developer from inside of the developing container toward an image bearing member by rotations thereof in the same rotational directions. The developer is fed by the first developer carrying member to and then is fed by the second developer carrying member to a latent image formed by the image bearing member. First and second magnetic field generation members are provided in the first and second developer carrying member fields, wherein the first magnetic field has a first magnetic pole disposed at a position substantially opposed to the image bearing member, and a second magnetic pole disposed at a position substantially opposite the second developer carrying member and having a polarity opposite the first magnetic pole. The second magnetic field generation member has a third magnetic pole disposed at a position substantially opposite the first developer carrying member and having the same polarity as the first magnetic pole. Magnetic forces A, B and C provided by the first magnetic pole, the second magnetic pole and the third magnetic pole, respectively satisfy: |A||B||C|.