Formwork is one of the essential elements of construction work in traditional reinforced concrete building construction. In addition to being complicated work, formwork is labor intensive and requires numerous, highly-skilled formwork carpenters. Labor accounts to over 50% of the cost of formwork, a large percentage relative to other types of basic construction work. To increase formwork efficiency, it is necessary to improve work methods. While productivity of formwork has been the focus of previous studies, effective work data such as detailed work processes or man-hours were not sufficiently obtained. This paper reports on an observational study carried out on fifteen building construction projects using work-study techniques, specifically work processes, man-hours, and number of workers in each work process. It highlights the process analyses of a typical formwork construction project and discusses the results of a statistical analysis of labor productivity related to all construction projects.