Image-capturing apparatus meeting demands for high-image resolution and high-speed data capture during both still- and moving-document data-capture modes. Includes: a reading unit having first and second linear photoreceptors arrayed along an data capture sub-scanning direction, a delay circuit delaying output from the first photoreceptor, and an adding circuit adding delayed first-photoreceptor output to second-photoreceptor output; and a scanning unit illuminating from underneath the platen, and shiftable along it to guide linear reflected light from a document to the first and second photoreceptors. During a moving-document data-capture mode, the scanning unit is disposed in a data-capture position established at one edge of the platen to scan a document being conveyed, and when in a still-original data-capture mode, it is shifted from along the platen's opposite edge toward the one edge thereof to scan a stationary document.