This paper presents the Restitution Coefficient Control method by a free-flying space robot for capturing a floating target in space. One of the most difficult tasks by a space robot is to capture a floating object autonomously in space because too much momentum exchange might push the object away from the operational space of a space robot. In order to overcome this issue, the authors propose a new control method, named the Restitution Coefficient Control, for controlling the restitution coefficient between the manipulator hand of a space robot and a floating object. The restitution coefficient is defined through a simplified dynamics model, and the control input is derived from the inverse problem of the derivation of the restitution coefficient. The dynamics simulation verifies that the Restitution Coefficient Control is capable of realizing the restitution coefficient of zero.