This paper describes a research project that focuses on the intelligibility of pronunciation in English as a foreign language (EFL) learners. English could be called a lingua franca, or a language that makes communication possible between people who do not share a native language. In the globalized world, English need not be pronounced correctly, but can be pronounced with any accent as long as it is intelligible. The fact that Japanese speakers' English generally lacks intelligibility is attributed to the difference between Japanese and English. The aim of this study is to devise explicit instruction on the difference of the two languages in the phonetic system and the relation between letters and sounds. This experiment was executed in two junior high schools, with one as the treatment group and the other as the contrast group. The seventh-grade students in the treatment group were given instruction in the rules of phonics and the international phonetic alphabet (IPA), while the seventh-grade students in the contrast group were given normal instruction on pronunciation. The pronunciation test was administered in both groups before and after the year-long instruction. The recoded data from the test was assessed by a native English speaker with criteria of intelligibility. The results of the pre-and post-test proved that the treatment group exceeded the contrast group with a significant difference. It is anticipated that phonics and IPA instruction at the beginning of EFL learning would lay the foundations for students' development into English speakers who can pass in globalized society.