This thesis is a study of slang translation in the novel entitled ‘Diary of a Wimpy Kid’ and its translation ‘Diary Si Bocah Tengil’, describing the types of slangs found in the novel, and the strategies used by the translator in translating those slangs. The collected data of this study were analyzed through descriptive qualitative method using theories on Slang To-Day and Yesterday, book of Eric Partridge, and In Other Words, book of Mona Baker. They were analyzed by using these steps: classifying slangs from the novel by drawing tables and pictures based on types and the strategies of translation found in the novel, explaining both the types and strategies of translation used by the translator. The types of slangs found in the novel consist of three types, they are workmen’s, public schools and universities, and society. The strategies employed in translating slangs in the novel are translation by a more general word (superordinate), translation by a more neutral/ less expressive, translation by cultural subtitution, translation using loan word or loan word plus explanation, translation by paraphrase using a related word, translation by paraphrase using an unrelated word, translation by omission, and translation by illustration. This thesis also describes the contribution of the finding in teaching English-Indonesian Translation in English Language Education Department (PBI). The contribution consists of an accuracy analysis of translation in English novel translated to Indonesian language is used as an activity in learning English-Indonesian translation, and putting the strategy of translation used in translating slang in the Diary of a Wimpy Kid novel as a subject matter in English-Indonesian Translation class.