A method of generating a workflow of an image forming job is provided. The method includes providing a list of selectable first functions, receiving a user input for selecting a first function from the list of first functions, providing a list of second functions that are continuously executable to the selected first function by using information about output data of the selected first function, receiving a user input for selecting a second function from the list of second functions, and generating a workflow defined to sequentially execute the selected first function and second function.