The purpose of this study is to propose of standardized modular steel structure unit for productivity enhancement of productivity in modular factory. For the verification, comparison review in various points of view between existing modular steel structure unit and standardized modular steel structure unit based on recently completion of modular system buildings. This research is suggestion of enhancement of standardized steel structure’s members for better production workability. The research is based on (1) steel structure process which is most high rate (approximately 30%) of modular unit manufacturing process and (2) prototype unit size of $3M{\times}6M{\times}3.2M(H)$ among the most used in recently project. For the verification, comparison analysis between existing steel structure unit and standardized steel structure unit’s manufacturing process. The research result, one modular unit of standardized steel structure manufacturing process is reducting (1) 250,042won production cost, (2) 3 hours and 49 minute of production time. Also, (3) increase the factory area availability of $203.84m^2$.