Image forming apparatus

An image forming apparatus comprising:

• a rotatable image bearing member;
• a developing device for developing with a toner an electrostatic image formed on said image bearing member;
• a first charging member for electrically charging said image bearing member in contact with said image bearing member;
• a second charging member, provided downstream of said first charging member and upstream of said developing device with respect to a rotational direction of said image bearing member, for electrically charging said image bearing member in contact with said image bearing member;
• a first power source for applying a DC voltage to said first charging member;
• a second power source for applying an oscillating voltage, in the form of a DC voltage biased with an AC voltage, to said second charging member;
• a detecting device for detecting a DC current passing through said second charging member;
• and
• a controller for controlling, when the oscillating voltage is applied to said second charging member while the DC voltage is applied to said first charging member, the DC voltage applied to said first charging member so that the DC current detected by said detecting device falls within a predetermined range including zero.