In this research, a small crawler-type searching robot driven with the pair of flexible shafts is proposed. It is capable of being effectively utilized for a search inside of rubble to quickly search for victims when a disaster such as an earthquake occurs. Since the crawler robot does not have to mount any power unit on the body, it is possible to construct the body of relatively light weight. Furthermore, since any electrical power source is not mounted on the body, the crawler robot can perform a searching operation under a sodden environment without additional waterproofing. To construct the proposed movement mechanism, we have to devise the structure of the flexible shafts. The flexible shafts are formed by inserting torque transmission driving wires (inner shafts) into tubes (outer tubes). In this paper, we investigate the characteristics of the outer tubes and the torque transfer characteristics of the flexible shafts. Then we improve the robustness of the outer tubes and the structure of the flexible shafts to enable a high-speed movement of the crawler robot.