The purpose of this study is to confirm that various optional insertion phenomenon is caused by the intentional articulation of the speakers and to discuss from metapragmatic perspective. The discussion contents are as follows. First is the optional insertion of ‘ㄴ’. The type ‘니깐요’ which is an form varied from ‘니까요’ by insertion of ‘ㄴ’ is derived by representation of metapragmatic implicature in order to emphasize the reason of the following sentences. Second is the optional insertion of ‘ㄹ’. Related to irregular conjugation, ‘[눌르고], [질르고]’ is used in real life by insertion of ‘ㄹ’ to ‘누르고, 지르고’. Similarly, ‘ㄹ’ is added to connective ending ‘려고’ and ‘하려고→[할려고], 자려고→[잘려고]’ is used. ‘ㄹ’ insertion phenomenon in both irregular conjugation and connective endings, ‘ㄹ’ is added under ‘(C)V$ㄹV(C)’ environment and realized into ‘(C)Vㄹ$ㄹV(C)’ type. In this sense, these phenomenon falls into same category and is also representation of metapragmatic implicature. Third, in internet language, various phoneme are added. In ‘갔을까낭, 죠아용’, insertion of ‘ㅇ’ expresses softness and cuteness, in ‘넵(←네), 받아랏(←받아라)’, insertion of obstruent expresses temperateness and decisiveness. Even though it is not an insertion of phoneme, word-initial glottalization phenomenon of which the phoneme is varied by insertion of [Tense] features is an articulation reflecting the psychological status and expectation of the speakers. Also, it is confirmed that phoneme insertion and word-initial glottalization phenomenon in internet language are also representation of metapragmatic implicature. (Chungnam National University)