An image capturing apparatus operable to capture an image of a target object by optically scanning the target object by moving in a predetermined scanning direction, the apparatus comprising: a plurality of light-receiving devices (11, 21) that are disposed on a light-receiving surface of the image capturing apparatus and configured to accumulate an electric charge according to an amount of light received from a light detection window, wherein the plurality of light-receiving devices (11, 21) are arranged in the scanning direction on the light-receiving surface, wherein a length of the window in the scanning direction is shorter than a length in the scanning direction of an area defined as one pixel of the target object, and wherein, in said area, the light-receiving device (11, 21) is arranged to receive light over the entire width in the scanning direction; and an output device configured to output the electric charge accumulated by the light-receiving device (11, 21) when the light-receiving device (11, 21) has completed the optical scanning of the area defined as one pixel, wherein the plurality of light-receiving devices (11, 21) are configured such that, for a present light-receiving device among the plurality of light-receiving devices which is disposed adjacent to a prior light-receiving device in the scanning direction, accumulation of an electric charge of the present light-receiving device starts when a period of time has elapsed since the prior light-receiving device has started to accumulate an electric charge, where said period of time is obtained by multiplying a distance between an upper end of the light detection window of the prior light-receiving device and an upper end of the light detection window of the present light-receiving device by a speed of the scanning; and the output device is configured to add and output the electric charges accumulated by the plurality of light-receiving devices. a plurality of light-receiving devices (11, 21) that are disposed on a light-receiving surface of the image capturing apparatus and configured to accumulate an electric charge according to an amount of light received from a light detection window, wherein the plurality of light-receiving devices (11, 21) are arranged in the scanning direction on the light-receiving surface, wherein a length of the window in the scanning direction is shorter than a length in the scanning direction of an area defined as one pixel of the target object, and wherein, in said area, the light-receiving device (11, 21) is arranged to receive light over the entire width in the scanning direction; and an output device configured to output the electric charge accumulated by the light-receiving device (11, 21) when the light-receiving device (11, 21) has completed the optical scanning of the area defined as one pixel, wherein the plurality of light-receiving devices (11, 21) are configured such that, for a present light-receiving device among the plurality of light-receiving devices which is disposed adjacent to a prior light-receiving device in the scanning direction, accumulation of an electric charge of the present light-receiving device starts when a period of time has elapsed since the prior light-receiving device has started to accumulate an electric charge, where said period of time is obtained by multiplying a distance between an upper end of the light detection window of the prior light-receiving device and an upper end of the light detection window of the present light-receiving device by a speed of the scanning; and the output device is configured to add and output the electric charges accumulated by the plurality of light-receiving devices.