This paper proposes a surgical manipulator with workspace-conversion ability for both minimally invasive surgery (MIS) and open surgery. The focus of the proposed surgical manipulator is on its potential use in places such as battlefields, army camps, and rural areas rather than in civilian hospitals. The proposed surgical manipulator has a workspace for MIS with a virtual remote center of motion and has a workspace for open surgery like that of an articulated manipulator. The mechanism of the surgical manipulator is proposed and implemented in this paper. A new distal rolling joint with two spiral wire ropes is also implemented. Several experiments to validate the feasibility of the surgical manipulator were carried out. Two fundamentals of laparoscopic surgery tasks were performed to compare the performance of the surgical manipulator with other MIS systems. The workspace conversion from MIS to open surgery was implemented. The workspace-conversion ability enables the surgical manipulator to attach or detach the surgical tool unit without human assistance or an assistant robot.