This paper proposes a novel easy-to-use camera-based tangible controller for cellular phone applications. It realizes continuous analog input by tracking a marker at the top end of a controller device attached to the embedded camera. In contrast to the conventional keypad which enables limited operability to four discrete directions, the proposed controller brings not only an unconstrained continuous input to arbitrary directions but also continuous input for depth and for a rotation angle. In order to evaluate operability, we conducted a user experiment of time trial for path tracing, and the results showed that the subjects completed the task with the proposed controller in 27.9% less than with the conventional keypad input. Categories and Subject Descriptors