Charging device and image forming apparatus

An image forming apparatus adapted to form a fixed toner image on a recording medium by way of a process of electrically charging a photosensitive body being moved in a predetermined moving direction and producing an electrostatic latent image on the photosensitive body when being exposed to light so as to carry a toner image as a result of developing the electrostatic latent image and ultimately by transferring the toner image onto the recording medium and fixing the transferred image, the image forming apparatus comprising:

• a charging member that electrically charges the photosensitive body;
• a power source adapted to supply an electric power showing a voltage waveform obtained by superimposing an AC voltage on a DC voltage to the charging member
• a contact member arranged downstream relative to the charging member as viewed in the moving direction of the photosensitive body and adapted to contact the photosensitive body directly or by way of a predetermined intermediary medium;
• an ammeter that gauges an electric current caused to flow through the contact member due to the electric charge on the photosensitive body electrically charged by the charging member and moved to the position contacting the contact member without effectuating exposure and development;
• and
• a power source control section that controls the electric current of the AC component supplied to the charging member by the power source on the basis of the electric current gauged by the ammeter.