An image forming apparatus used in an image forming system, the image forming system including: a receiving portion that receives a printing instruction from an operator; an image forming portion that forms an image based on print data in accordance with the printing instruction; an authenticating portion that authenticates the operator as a pre-registered authenticated user; a storing portion that stores the print data and that is capable of storing related print data associated with the authenticated user and unrelated print data not associated with the authenticated user; and a displaying portion that displays information to the user, CHARACTERIZED IN THAT the image forming apparatus comprises: a controlling portion that performs control processing based on a program, and that is configured to: cause, when the operator issues the printing instruction via the receiving portion, the displaying portion to display information regarding the related print data associated with the authenticated operator among the print data stored in the storing portion, based on that the operator has been authenticated as the authenticated user in the authenticating portion, and cause, when the operator issues the printing instruction via the receiving portion, the displaying portion to display information regarding the unrelated print data among the print data stored in the storing portion, based on that the operator has not been authenticated as the authenticated user in the authenticating portion. a receiving portion that receives a printing instruction from an operator; an image forming portion that forms an image based on print data in accordance with the printing instruction; an authenticating portion that authenticates the operator as a pre-registered authenticated user; a storing portion that stores the print data and that is capable of storing related print data associated with the authenticated user and unrelated print data not associated with the authenticated user; and a displaying portion that displays information to the user, CHARACTERIZED IN THAT the image forming apparatus comprises: a controlling portion that performs control processing based on a program, and that is configured to: cause, when the operator issues the printing instruction via the receiving portion, the displaying portion to display information regarding the related print data associated with the authenticated operator among the print data stored in the storing portion, based on that the operator has been authenticated as the authenticated user in the authenticating portion, and cause, when the operator issues the printing instruction via the receiving portion, the displaying portion to display information regarding the unrelated print data among the print data stored in the storing portion, based on that the operator has not been authenticated as the authenticated user in the authenticating portion. cause, when the operator issues the printing instruction via the receiving portion, the displaying portion to display information regarding the related print data associated with the authenticated operator among the print data stored in the storing portion, based on that the operator has been authenticated as the authenticated user in the authenticating portion, and cause, when the operator issues the printing instruction via the receiving portion, the displaying portion to display information regarding the unrelated print data among the print data stored in the storing portion, based on that the operator has not been authenticated as the authenticated user in the authenticating portion.