To provide an image forming apparatus that processes output of a next printed matter without making a user replenish tab paper when the tab paper runs out in case that excessive tab paper generated while processing the output of the printed matter is being ejected.

An MFP 2 ejects the excessive tab paper that is not printed after print processing of the tab paper by defining the predetermined number of tab paper as a printing unit. The MFP 2 determines whether or not paper-out of the tab paper during ejection processing of the excessive tab paper occurs, and stops the ejection processing of the excessive tab paper when determining that the paper-out of the tab paper occurs during the ejection processing of the excessive tab paper. Moreover, the MFP 2 prints paper as a printing unit for next printing.