An image capturing device unit capable of reducing noise generated in image signals due to power supply. A pixel portion of an image capturing device has pixels arranged in a matrix in first and second directions perpendicular to each other. Output lines are arranged in parallel to the second direction, for reading out pixel signals in the second direction for each of groups of pixels arranged in the first direction. A power supply wiring is arranged on a substrate surface different from a surface on which the image capturing device is mounted and supplies power to the device, and includes a draw-out wiring portion arranged to be routed along the second direction in a pixel portion area which overlaps the pixel portion when the device is projected onto the substrate in a third direction perpendicular to the first and the second directions.