An image forming apparatus includes: a connection part for enabling an external memory apparatus to be connected thereto; a data retrieval part for retrieving output target data stored in the external memory apparatus connected to the connection part; an output part for outputting output target data retrieved from the external memory apparatus; a data writing part for writing saving target data into the external memory apparatus connected to the connection part; a determination part for, when the external memory apparatus is connected to the connection part, determining which one of a first mode and a second mode is a mode of a job intended for execution, wherein the first mode is a mode in which output target data stored in the external memory apparatus is retrieved and outputted and wherein the second mode is a mode in which saving target data is written and saved into the external memory apparatus; and a mode setting part for, based on the result of the determination made by the determination part, setting either one of the first mode and the second mode as the mode of the job intended for execution.