A developing device 10 has a voltage application member 18 which is in contact via a toner layer with a developing roller 14 that rotates while holding the toner layer on its outer peripheral surface. To the toner layer, the voltage application member 18 applies a relatively low voltage in an upstream-side contact portion with respect to a rotational direction of the developing roller 14, and applies a relatively high voltage in a downstream-side contact portion thereof.