An image-capturing device including a body, an optical module and an upper cover is provided. The body has an upper surface and a first inclined plane, wherein the upper surface has an image-capturing area, and the first inclined plane is connected and located adjacent to the upper surface. The optical module is movably disposed in the body and is for capturing an image of a document inside the image-capturing area. The upper cover has a lower surface and a second inclined plane, wherein the second inclined plane is connected and located adjacent to the lower surface. When the upper cover is closed upon the body, the second inclined plane is placed atop the first inclined plane. The included angle between the second inclined plane and the lower surface is at least equal to the included angle between the first inclined plane and the upper surface and less than 180 degrees.