Now at the time in which software industry has become the core of national competitiveness, estimating the accurate budget at the initial phase of software business got recognized as one of the important factors in the success or failure of software business. This paper proposes improved software maintenance and operation cost estimation guideline in order to estimate more accurately after surveying realistic problems. It also defines the task of software maintenance and operation and sets the scope of them. It presents the model for fixed cost to make accurate estimation, which allow the regular task.
Furthermore, it proposes the model for variable cost to make rational estimation, which allow the maintenance and문 operation jobs.