The present invention enables image data with good S/N and high resolution to be obtained reliably in a short reading time. A CCD 102 is formed by arranging line sensors, in which detecting elements having a time integration effect are arranged in a direction orthogonal to a relative movement direction in which the CCD 102 moves relative to an original, in a plurality of columns in the relative movement direction. A signal processing unit 107 detects pixel components on the basis of a model for separating first pixel values obtained in a processing unit time by the CCD 102 into a plurality of the pixel components corresponding to detection positions of the object being detected, and generates second pixel values corresponding to the detection positions of the object being detected on the basis of the detected pixel components. The present invention is applicable to scanners.