An image forming apparatus comprising: a communicating unit that receives, from a server apparatus connected to a network, an image forming job being a unit of execution of an image forming process of a first protocol or a second protocol other than the first protocol, the first protocol containing a series of process instructions and print data that allow the image forming process to be performed from an interrupted point when the image forming process is resumed after being interrupted; an image-formation processing unit that performs the image forming process by executing the image forming job; and a priority processing unit that, when an image forming process of an image forming job of the first protocol is interrupted and when receiving both an image forming job of the first protocol related to the interrupted image forming process and an image forming job of the second protocol, preferentially selects the image forming job of the first protocol related to the interrupted image forming process, wherein the image-formation processing unit successively performs the interrupted image forming process by executing the preferentially-selected image forming job of the first protocol, characterized by the image forming apparatus further comprising: a job determining unit that determines, when receiving a plurality of image forming jobs of the first protocol after the image forming process of the image forming job of the first protocol executed by the image-formation processing unit is interrupted, whether each of the plurality of received image forming jobs is an image forming job of the first protocol related to the interrupted image forming process, wherein when each received image forming job is the image forming job of the first protocol related to the interrupted image forming process, the priority processing unit preferentially selects each received image forming job as an image forming job of the first protocol related to the interrupted image forming process. a communicating unit that receives, from a server apparatus connected to a network, an image forming job being a unit of execution of an image forming process of a first protocol or a second protocol other than the first protocol, the first protocol containing a series of process instructions and print data that allow the image forming process to be performed from an interrupted point when the image forming process is resumed after being interrupted; an image-formation processing unit that performs the image forming process by executing the image forming job; and a priority processing unit that, when an image forming process of an image forming job of the first protocol is interrupted and when receiving both an image forming job of the first protocol related to the interrupted image forming process and an image forming job of the second protocol, preferentially selects the image forming job of the first protocol related to the interrupted image forming process, wherein the image-formation processing unit successively performs the interrupted image forming process by executing the preferentially-selected image forming job of the first protocol, characterized by the image forming apparatus further comprising: a job determining unit that determines, when receiving a plurality of image forming jobs of the first protocol after the image forming process of the image forming job of the first protocol executed by the image-formation processing unit is interrupted, whether each of the plurality of received image forming jobs is an image forming job of the first protocol related to the interrupted image forming process, wherein when each received image forming job is the image forming job of the first protocol related to the interrupted image forming process, the priority processing unit preferentially selects each received image forming job as an image forming job of the first protocol related to the interrupted image forming process. a job determining unit that determines, when receiving a plurality of image forming jobs of the first protocol after the image forming process of the image forming job of the first protocol executed by the image-formation processing unit is interrupted, whether each of the plurality of received image forming jobs is an image forming job of the first protocol related to the interrupted image forming process, wherein when each received image forming job is the image forming job of the first protocol related to the interrupted image forming process, the priority processing unit preferentially selects each received image forming job as an image forming job of the first protocol related to the interrupted image forming process.