In this paper, we analyze error cases of the unconditional usage of the conjunctive particle “-to” by native Chinese learners in the composition corpus and examine the causes of error. The characteristics of the various misuse patterns and the reasons for them are: (1) learners use “toiuto” as a reminder of the topic, often about specific things or people. The main reason for the misuse is the difference between the range of topics reminded by “toiuto” and the range of topics reminded by the Chinese words “shuoqi” and “shuodao.” (2) The misuse of “niyoruto” can be divided into two parts: the mixed-use with “niyotte” and the misuse of “quoting”. The mixed-use with “niyotte” is due to the similarities in pronunciations, forms, meanings and its translations in Chinese, because they are both derived from the verb “yoru”. In contrast, the misuse of quoting seems to be influenced by the meaning of “yoridokoro.” (3) “Karamiruto” is used to express the basis of a judgment. This misuse is related to the meaning of the verb “miru” and its translation in Chinese “cong … laikan.” (4) “Ninaruto” is difficult to use as a simple “topic reminder.”