An image forming apparatus, for example, that is capable of accurately writing information into a developing unit or the like having an element is achieved. An image forming apparatus comprises: an attach/detach section to and from which a developing unit having an element into which information can be written and a developer containing section can be attached and detached; a photoconductor on which a latent image can be formed; a writing member for writing information into the element; and an AC voltage supply section for supplying an AC voltage. During a period from a start to an end of an image forming process, the writing member writes information into the element of the developing unit attached to the attach/detach section when the AC voltage supply section is not supplying an AC voltage.