Japanese has borrowed many words from English through contacts with English-speaking countries since the mid-19th century. The borrowed words have been integrated into the Japanese lexicon, observing phonological and morphological rules of Japanese. Among the types of loanwords from English, this research examines abbreviated English words in Japanese by classifying them into five categories: (i) consonantal abbreviations, (ii) acronyms, (iii) initialism (iv) clipping, and (v) blending. Examination of the present data shows that more than half of the tokens are examples of clipped words, suggesting that clipping is the most frequently used method of abbreviating borrowed words into Japanese. Initialism comes second in making abbreviated expressions, even applying to newly coined Japanese English (JE) words. After that, this study explores linguistic motivations which are responsible for the formation of abbreviations in English loanwords. It shows that economy and distinctiveness/contrastiveness are two most important motivations for the formation of abbreviations of English loanwords in Japanese.