In the software education imparted in universities, especially in the evaluation of beginners' practice assignments, functionality of software is emphasized, while evaluation of code quality such as adequateness of modular partitioning and readability of code usually takes the back seat. It is desired to feedback quality related evaluation to students from early stages of learning as the adverse effect of quality related problems comes to surface as the size of software increases. Although instructors understand this, since this requires investment of large amount of resources for development and maintenance of tools for measuring the quality of code, it has become a bottleneck resulting in the aforementioned situation. In the present study, we applied source code quality diagnostic tool, developed as an open source program, to the programs submitted by students. While describing the method for detecting typical mistakes which students are prone to commit based on the data obtained, we have described the method for effectively using highly general purpose source code quality diagnostic tool in education.