A double side image scanner includes a frame, a two-way roll feeder, a one-way roll feeder and an image sensor. The frame includes a track that has an entrance, a scanning line joined to the entrance and a circuit line joined to the scanning line. The circuit line is designed to return the medium to the scanning line. The circuit line has a junction point where the circuit line meets with the scanning line, an inlet through which the medium comes into the circuit line from the scanning line and an outlet through which the medium goes out of the circuit line toward the scanning line. A driving means mounted to the frame for driving the two-way roll feeder and the one-way roll feeder. The image sensor obtains image data by scanning the front and rear surfaces of the medium.