Image forming apparatus with document box for storing input data relating to execution conditions of functions executable by the image forming apparatus

An image forming apparatus includes an execution controller for operating a function to be operated with function settings provided in a program. When a program is received by a program receiver, the execution controller causes a display controller to display box data stored in a document box related to the received program on a box data selection screen. Subsequently, after the box data selected and input on the displayed box data selection screen is received by a box data receiver, the execution controller handles the received box data as input data and operates the function to be operated with the function settings provided in the received program.