We have no standardized cost code system for domestic public construction projects. It have been used various cost codes in public construction projects, and it makes it so difficult to accumulate and analyze cost data of construction projects. In order to develope the standardized cost code system, we analyzed the usage of the standard cost code systems which have been developed and the BoQ items of public construction projects in 3 years. As a result, we suggested the standardized cost code system for BoQ items and it has been reviewed by some construction cost experts. We have applied the standardized cost code system to public construction projects and verified the usability of it. In case studies, over 80% of cost items in BoQ can be applied by standardized cost code system from this paper. The standardized cost code system from this paper is expected to bring more efficiency to our construction management practices.