If position detection is performed correctly, connection switch 161 is connected through a control signal and transmit power control circuit 162 carries out transmit power control based on reception power of a signal combining direct wave signals and delay wave signals. The water-absorbent resin obtained by the method for producing a water-absorbent resin of the present invention is excellent in properties such as water-retention capacity, water-absorption capacity under load, and gel strength, and also gives consideration to safety of the water-absorbent resin by reducing water-soluble substance. In one of the preferred embodiments of this invention, each wraps is configured to permit the ends of the fingers to extend from the wrap; and, a complimentary hook and loop array is affixed to each of the palm side and backhand side of each wrap, respectively. The reduction ratio used by the resolution converting section is encoded, and the transmitting section transmits this encoded reduction ratio along with encoded data on the binary picture. One of the variable-length coding tables is selected according to mode, quantization step size and scanning position, and the orthogonal transform coefficients according to the selected variable-length coding table are variable-length-coded.