Abstract
Recently the use case model has been a common documentation of writing requirement in object oriented development projects. Using the use case as a basis of the estimation, we can expect to improve accuracy of estimation results and to manage the size of projects continuously from early phase of the development project to the end of it. In this work, we have proposed estimation method of the number of test-cases based on the use cases and then the project effort estimation method based on the number of test-cases by using our proposal. We can utilize plenty of data saved by a number of projects for making a model of estimation with our proposal. In this paper we report our partial practical estimate-models, and also we discuss the possibility of the project effort estimation technique as a new solution.