1. An image forming apparatus operated by a mobile terminal, comprising: a function performance information storage section which converts an individual performance value indicating performance of each of elements of hardware or software used at the time of realizing a function provided in the image forming apparatus into a point based on a predetermined weighting to the individual performance value and stores a total of all the converted points for the elements as function performance information representing performance of the function; a function performance information receiving section which receives a total of points into which respective individual performance values indicating performance of elements of hardware or software used at the time of realizing a function provided in the mobile terminal are converted as function performance information representing performance of the function from the mobile terminal; and a function selection section which compares the function performance information of the image forming apparatus with the function performance information of the mobile terminal to select the function for which the performance of the image forming apparatus is determined to be superior, wherein the image forming apparatus transmits the information representing the function which is not selected by the function selection section to the mobile terminal, and performs the processing of the function selected by the function selection section.