Intention reading is considered as an important issue in the field of human-robot interaction (HRI). Specifically, for cooperation between a human and a robotic system, a robot should be aware of a given situation and human intention, which necessarily requires high-level knowledge and balanced interaction. For the disabled and elderly, who may not be familiar with manipulating robotic systems, intention sharing between two different agents is preferable for accurate intention reading. In this paper, we focus on the effect of intention sharing of a human user and a robot assistant to improve cooperation.