An image forming apparatus includes: a photoreceptor including a surface layer; a storage that stores a target value of a variation of a film thickness of the surface layer; and a hardware processor that acquires a variation of the film thickness in a first period within which the photoreceptor rotates a predetermined number of times, and sets a margin that is an amount of a portion for allowance with respect to a proper value of a parameter related to control of the photoreceptor, the margin being to be employed after the first period.