It is necessary to improve not only plant system but also human system for maintenance to optimize maintenance for industrial plants like nuclear power plants. Codes and standards for design and construction of plant system have been already well developed. On the contrary, standardization of documents relating to human system including maintenance implementation plan, field work procedures etc. have poorly developed. So we have established the special committee in Japan Society of Maintenology to standardize documents relating to human system for maintenance. This paper reports such necessity and points of this activity including the current status of the committee.