A sheet feeding device having; a mounting portion capable of accommodating a stack of sheets; a blowing device that blows air onto the stack placed in the mounting portion, thereby floating at least a top sheet from the stack; a suction/transportation mechanism that includes a suction belt provided above the mounting portion and attracting the top sheet floated by the blowing device to transport the attracted sheet toward a transportation path; an image pickup device disposed so as to capture an image of the floated top sheet and the next sheet therebelow; and an illuminating device that emits light toward an area to be captured by the image pickup device. The light emitted by the illuminating device illuminates a plane in a direction approximately normal thereto, the plane including the closest end surface of the stack of sheets to the image pickup device.