As interests in the quality of data in database systems are growing recently, analysis and improvement of data quality in databases have been an important issue. However, there has yet to be a clear agreement on how to reasonably calculate the total cost of such project. In this paper, based on real project data and budget statistics, we develop a model to estimate the cost for quality analysis and improvement project of a database. We first conduct statistical analysis to build our basic model. Throughout this analysis, we have identified factors that determine the scale of works required to conduct the project and eventually determine the cost. In addition, we have identified factors that determine the complexity of the project. These factors can adjusts the cost determined by the scale of works. Our model is verified and improved by surveys on experts. We apply our model to newly conducted projects and observe that our model estimates the cost of each project reasonably well.