With the increasing popularity of wearable computing, emerging techniques allow novel interaction modalities to be transferred from portable devices to the human body itself. One promising approach is to appropriate the skin for input interface. While researches explore the potential of using the skin as an input surface, we show an alternative interaction modality-SkinMotion. SkinMotion reconstructs human motions from skinstretching movements. In this workshop, we discuss the potential applications of SkinMotion. In addition, we explore one specific instance - finger motion detection using the skin movement on the dorsum of the hand. Results show that SkinMotion can achieve 5.84° estimate error for proximal phalanx flexion on average. We expect SkinMotion to open new possibilities for skin-based interactions and to extend new boundaries of on-body technologies.