IMAGE FORMING APPARATUS

A relationship between a light amount of an exposure portion and a surface potential according to a use amount, a first detection light amount corresponding to a prescribed surface potential in the relationship where a use amount of a photosensitive member is a first use amount and a second detection light amount corresponding to the prescribed surface potential in the relationship where the use amount of the photosensitive member is a second use amount, which is greater than the first use amount, are acquired. The exposure portion changes, as an electrostatic image forming light amount, a first image forming light amount representing a setting value under the first use amount to a second image forming light amount representing a setting value under the second use amount on the basis of a ratio of the first detection light amount to the second detection light amount.