Natural Orifice Translumenal Endoscopic Surgery (NOTES) is a type of minimally invasive surgery. This surgery needs working space for operating the endoscope, but there is no space for it in body cavity. Therefore, we have been developing a surgical tool system which can be inserted from the mouth and ensure space in body cavity. We use magnets and a tool to ensure space, like in abdominal wall lifting method, without use of wire. In this paper, we designed and realized a system which used a tool consisting of link mechanism and magnets. The link mechanism consists of four-bar linkage and a compression spring. It can be driven only by pulling wires, changing the diameter of the tool. We designed this surgical tool prototype, analyzed the stress and did basic experiments.