This paper presents an initial conceptual design of a wearable manipulator for supporting astronaut extravehicular activity (EVA). The proposed robot system acts as a third hand or eye of astronauts, and supports them by handling tools or recording their tasks using camera during EVA with the manipulator itself attached to the space suit or handrail. The initial conceptual design includes the system concept, requirements, elemental technologies and operational scenarios which are defined on the basis of the interviews to astronauts and operators. The prototype of the manipulator, especially robotic hand or end effector is also discussed in this paper for estimating the feasibility of the proposed robot system in the future manned space activities.