The objective of the study was to analyze differences and similarities of English and Korean language with used contrastive analysis. CA is the systematic comparison of two or more languages, with the aim of describing their similarities and differences. This research conducted CA research between English and Korean. This study intended to explore about Koreanization of English noun words in Korean course text book in the term of vocabulary to find phonology different among two languages. This study attempted to examine kinds of Koreanization of English noun words and the rules how to pronounce the English noun words in the Korean course text book when it change into written Korean as hangeul. The Korean alphabets. The Korean textbook the title Panduan Belajar Mandiri Untuk Orang Indonesia consisting of 60 chapters, Published by HRD Korea. The methodology, researcher used analysis text to analyse what kind of Koreanization of English words in the Korean textbook. The aim of this study is to describe How the process of English words change into written Korean found in the Korean textbook. The instrument was the researcher itself to collect and analysis the data. There were several steps of data collection. They were reading, identifying, grouping, analyzing and elaborate. There were three steps of analyzing data of qualitative data used in this research. They were data reduction, data display, and conclusion. The result of this research, it was report that there were 104 types of English words that experienced Koreanization in the 60 chapters of the Korean course textbook and only 28 chapters that had Koreanization of English noun words. The kinds of English noun words found getting Koreanization are deletion, insertion and code-mix combination. Meanwhile, in the rules of changing English words to be written in Korean. It is divided into three, namely deletion, insertion and code-mix combination. Differences in pronunciation that occur between English and Korean occur due to several phoneme differences between English and Korean, there are 8 consonants /r/, /v/, /z/, /f/, /c/, /sh/,/h /,/l/ and 5 vowels /u/, /e/ eu/, /ae/, /i/ which changed from English to Korean and, there are 10 words that mix English and Korean words so that they become Korean. Those are Sinyong-khadeu, Woegugin sentho, Phisi-bang, Menyu-phan, Eumsik-menyu, Khompyutho-suob, Bose-jongnyujang, Inthonet-jonhwa, Saengil-phathi and Yeneung-pheurogeuram. Example, Credit card in in English, in Korean is 신용카드 (sinyeong-khadeu), sinyeong is words from Korean and khadeu is from English (card). Then, combined become Korean words credit card. In teaching and learning English as second language or learning English as foreign language, contrastive analysis is really helpful for both the teachers and the students, because we will know the differences and similarities between source language (L1) and target language (L2). Especially for English teachers who teach with two languages and international students. Like English to Korean or Korean to English. This makes it easier to communicate and understand with L1 or L2 when teaching international students who speak English with their native language pronunciation such as Korean students to England or English students to Korea.This research will help the teacher notice their pronunciation correct or wrong and correct the students with the standard pronunciation to the target language. And also, for international students who want to learn other languages other than their source language or polyglot students. Therefore, it is easy for them to learn and adjust to the target language. So that, they do not incorporate the system of our source language to target language, because each language has distinct system. Because, Korean here has more limited sounds than English, making Korean speakers who learn English or English speakers who learn Korea feel the strenuous effort to find the right point.