First integrating circuits 110 convert electric currents from one group of photosensitive portions electrically connected to each other in a plurality of pixels arranged in a first direction into voltages, and output the voltages. First S/H circuits 130 hold and output the voltages outputted from the first integrating circuits 110. A first maximum value detecting circuit 140 detects the maximum value of the voltages outputted from the first S/H circuits 130. First level shift circuits 170 shift levels of the voltages outputted from the first S/H circuits 130. A first A/D converter circuit 180 sets a range from the maximum value detected by the first maximum value detecting circuit 140 to a value smaller than the maximum value by a predetermined value as an A/D conversion range, and converts the voltages outputted from the first S/H circuits 130 into digital values within the A/D conversion range.