Wakamono kotoba is one of a variety of language created by the young people in Japan. This study was conducted to know wakamono kotoba which appeared on social media twitter. The purpose of this study are to know the type of wakamono kotoba and the word formation of wakamono kotoba on social media twitter. The data on this study was taken from the tweet with vulnerable age of users are 15-27 years old, based on trending topic of twitter period January until April 2018. This study is descriptive method with qualitative approach. The data obtained will be grouped based the type of wakamono kotoba and the word formation. The result of this study is there are many variations type and word formations of wakamono kotoba. From 35 data wakamono kotoba had been found, there are wakamono kotoba type tanshuku-go, KY shiki-go, gyaru-go and netto-go. Word formations that has been found are clipping, borrowing and reduplication. Besides, there are two or more word formations such as compounding-clipping, borrowing-clipping, clipping-affixation and borrowing-clipping-affixation.