A multi-mode scanning device includes a background element, a transparent platen, first and second light sources and an optical module. The first light source outputs visible light to irradiate the background element and an original on the transparent platen to generate first and second light, respectively. The second light source outputs invisible light to irradiate a combination of the background element and the original to generate third and fourth light. The movable optical module receives the first to fourth light and generates sensing signals, and obtains visible light information and invisible light information representative of the original according to the sensing signals. The original is disposed between the background element and the optical module. The first light source and the optical module are disposed on a same side of the background element. The optical module and the second light source are disposed on different sides of the background element.