Cell room as a workstation is located electrolyser that produces chlorine gas with a stable and continuous electrolysis process, the chlorine gas produced as the main raw material along ethylene gases for the manufacture of ethylene dichloride or EDC in the DC Reactor. Cell room has a very large number of valves that vary greatly in terms of model, service and size but in one place that is not wide so that the valve location is often close together sometimes even coincide. The objective of this research is to analysis work posture using RULA method on operator cell room electrolyser. Valve layout that is difficult to reach and heavy rotation to operate also sometimes the operator must squat and bend when operating most of the valves. The results show RULA identified the high risk in performing job task in cell room electrolyser. A survey method developed for the usefulness of ergonomic investigations in the workplace, in which occupational upper body muscle disease is identified. This tool does not require special equipment in providing posture measurements of the neck, back, arms and upper body as the function of the muscles and the external burden of the body. As a result, several design and tools were proposed to increase the operator’s performance in cell room electrolyser.