When a station whose information has been kept stored in memory is again receivable a digital broadcasting receiver terminal can select the station immediately based on station selection information, without making a channel scanning in search for the station again. The image forming apparatus includes a plurality of photoconductors on which developer images having carrier rates different from each other are formed with corresponding liquid developers. Therefore, if the amount of expansion and contraction of the X-Y robot due to heat is obtained by picking-up an image of the camera reference mark by a board recognition camera and the component placing position is corrected on the basis of the amount of expansion and contraction, then an electronic component can be mounted in a prescribed position or almost in the prescribed position.