In this paper, we describe the development of a support system that facilitates the process of learning computer programming through the reading of computer program source code. Reading code consists of two steps: reading comprehension and meaning deduction. In this study, we developed a tool that supports the comprehension of a program's reading. The tool is equipped with an error visualization function that illustrates a learner's mistakes and makes them aware of their errors. We conducted experiments using the learning support tool and confirmed that the system is effective.