Patent ID: 8532512

Claim:
An image forming apparatus comprising: a charging unit which charges a surface of an image bearing member by contacting the image bearing member with a charging member to which a charging bias is applied, the charging bias being a voltage obtained by superimposing an alternative current voltage on a direct current voltage; an electrostatic latent image forming unit which forms an electrostatic latent image on the surface of the image bearing member which is charged by the charging unit; a developing unit which develops the electrostatic latent image by using a developing bias formed by the voltage obtained by superimposing the alternative current voltage on the direct current voltage; and a control unit which performs changing control of an alternative current frequency of the charging bias while maintaining a frequency ratio of an alternative current frequency of the developing bias to be an integral multiple of the alternative current frequency of the charging bias, wherein the control unit is configured to change the alternative current frequency of the charging bias within a predetermined range from a predetermined central frequency in the changing control of the alternative current frequency of the charging bias.