Humans have one own body. However, we can share a body with two different persons in a virtual environment. We have developed a shared body as an avatar that is controlled by two persons' actions. Movements of two subjects were continuously captured, and integrated into the avatar's motion with the ratios of 0:100,25:75, 50:50, 75:25, 100:0. They were not aware of integration ratios, and asked to reach cubes with the right hand. They felt body ownership and sense of agency to the shared avatar more when the responsible ratio was higher. The reaching path of the avatar's hand was shorter in the shared body condition (75:25) than the single body condition (100:0). These results suggest that we have some of body ownership and sense of agency to the shared body, and the task performance is improved by the shared body.