Depending on the growth of the construction industry, size of construction sites are becoming enlarged, and construction work is becoming diversified as well. However, this increases risks of safety accidents. In order to alleviate this problem, some large construction companies have implemented a Safety Patrol Management System (SPMS) in order to reduce accidents on construction sites. Aimed at the construction sites where SPMS has been applied, the purpose of this research is to calculate the proper number of SPMS safety mangers by comparing and contrasting the number of safety managers per person for each site with different sizes and the converted accident ratio. In addition, we also aim to calculate the adequate amount of SPMS safety management costs compared to the total amount of construction expenses required once SPMS is introduced.