In this paper, we present the Magnetic Marionette, a magnetically driven elastic controller that enables tangible interaction on mobile devices. This technique can determine eight different gestures in excess of 99% accuracy by sensing and tracking the magnets embedded on the controller. The advantage of this technique is that it is lightweight, battery-free, and inexpensive because it uses a magnetometer, which is already embedded in smart phones today. This simple and noble technique allows users to achieve richer tactile feedback, expand their interaction area, and enhance expressiveness without the need for hardware modification.