An image forming apparatus includes an image obtaining unit configured to obtain an image of a document, a document supplying unit configured to supply a document to the image obtaining unit, an image forming unit configured to form the image on a printing medium, a storing unit configured to store supply status information of the document, and a controller configured to perform a preparation for an image forming operation in response to at least one of the document being supplied to one of the image obtaining unit and the document supplying unit and an option setting command of the image forming operation being input. The controller, in response to the option setting command being input after the preparation for the image forming operation is stopped, is configured to perform the preparation for the image forming operation again based on the supply status information of the document.