A document image scanning device includes two scanning units provided along a document transportation path for scanning both sides of an original document. A plurality of transportation systems are classified into a first transportation system upstream of a first scanning unit and a second transportation system located front and back of first and second scanning units. The first and the second transportation systems are driven by first and second drive transmitting units, respectively. The first and the second drive transmitting units are distributed from an output shaft of one motor to transmit a driving force.