An image forming apparatus forms an image on a sheet by using a consumable material contained in a consumable material unit. The consumable material unit includes a storage medium. The storage medium stores first information and second information. The image forming apparatus includes a control section and a reading section. The controlling section performs pre-processing. The pre-processing is for starting the image formation and performed based on the first information. The reading section reads the first information from the storage medium and transmits the first information to the control section before reading the second information. The first information is essential for the pre-processing. The second information is processable by the control section during or after the image formation.