In order to develop effective teaching methods and computer-assisted language teaching systems for learners of English as a foreign language who need to study the basic linguistic competences for writing, pronunciation, reading, and listening, it is necessary to first investigate which vocabulary and grammar they have or have not yet learned. Identifying such vocabulary and grammar requires a learner corpus for analyzing the accuracy and fluency of learners' linguistic competences. However, it is difficult to use previous learner corpora for this purpose because they have not compiled all the types of linguistic data that we need. Therefore, this study aimed to solve this problem by designing and developing a new learner corpus that compiles linguistic data regarding the accuracy and fluency of the four basic linguistic competences of writing, pronunciation, reading, and listening. The reliability and validity of the learner corpus were partially confirmed, and practical application of the learner corpus is reported here as case studies.