Abstract. The economic developments and industrial progressions, the automatic operations were getting more wide-spread. However, currently in various operation occasions, the workers are still required to face how to operate all kinds of hand tooling and equipments. In the industrial cases, there were many opportunities to use hand grip strength to operate machines. Hand grip strength has received increasing attention from industrial engineers and ergonomic researchers. The relation between hand grip strength and tool's grip span was important issues in ergonomics. Occasionally, it was little research to conduct. This study aims at exploring the relationship of tool's grip span and hand grip strength. Seventy two subjects rose from volunteers' participators, including 29 males and 43 females. Dependent variables were maximum volitional contraction and hand gripping control (HGC-70% , target value 70% MVC). Three different diameters of grip span were significance differences in maximum volitional contraction and hand gripping control. The study finds that the best diameter of tool's grip span was 47.6 mm. The finding will be served as a reference for task design, instrument design as well as for disease protected for industrial staffs
