We present a new mobile interaction model, called double-side multi-touch, based on a mobile device that receives simultaneous multi-touch input from both the front and the back of the device. This new double-sided multi-touch mobile interaction model enables intuitive finger gestures for manipulating 3D objects and user interfaces on a 2D screen. Keywords Double-side Multi-Touch, Finger Touch Gesture, Mobile Interaction ACM Classification Keywords H5.2. [User Interfaces]: Input devices and strategies, Interaction styles.