A portable scanner includes a housing including a hollow upper housing and a hollow lower housing of which two ends are connected together to define a transmitting passage therebetween, a switching device rotatably mounted inside the upper housing, a first scanning device mounted on the switching device, and a document feeder for transmitting the document automatically through the transmitting passage. A first and a second scanning window are opened in and penetrating through two different sides of the upper housing respectively, wherein the second scanning window is communicated with the transmitting passage. The switching device together with the first scanning device are switched between a first scanning state that is the first scanning device faces the first scanning window for scanning the document manually, and a second scanning state that is the first scanning device faces the second scanning window for scanning the document automatically.