The purpose of this research is to study the effect of safety measure to construction productivity for ceiling activity by studying a construction of buildings in Bangkok. The safety system composed of (1) stable scaffolding system (2) providing clean and not slip walkways on the scaffold (3) installation of handrails not less than 0.90 meters in height (4) installing stairs (5) providing personal protective equipment for workers (6) are responsible for scaffolding and (7) scaffolding permit document. Cost of the safety system is 23908 baht or approximately 33 baht/m2. Productivity rates for prior and after the used of safety system are 1.57 and 1.41 m2. /person/hr. respectively. The productivity declines for approximately 10.19 % the working time for ceiling could take longer for 10.45 % and labor cost could increase for 10.19 %.