To find key factors not to drop out using learning analytics, we have added accumulated data such as the number of successes in learning check testing, the number of attendances to follow-up program classes, and etc., in addition to learning check testing ability scores performed at each lecture. Then, we have found key factors strongly related to the students at risk. They are the following. 1) Badly failed students (score range is 0-39 in the term ex-amination) tend to be absent for the regular classes and fail in learning check testing even if they attended, and they are very reluctant to attend follow-up program classes. 2) Success-ful students (score range is 60-100 in the term examination) attend classes and obtain good scores in every learning check testing. 3) Failed students but not so badly (score range is 40-59 in the term examination) reveal both sides of features appeared in score range of 0-39 and score range of 60-100. Therefore, it is crucial to attend lectures in order not to drop out. Students who failed in learning check testing more than half out of all testing times almost absolutely failed in the term examination, which could cause the drop out. Also, students who were successful to learning check testing more than two third out of all testing times took better score in the term examination.