本文在语言学研究理论基础上，通过分析日本英语学习者书面语中的典型错误，从数、性、格、人称、时态和词序六个方面重点讨论了由于语法范畴的差异性导致的语言错误，呈现了日本英语学习者在语言学习过程中的中介语发展进程，解释了他们的中介语特征。研究结果为进一步的语言研究提供了语言事实材料，同时也加深了外语教师对语言内部结构的理解，从而探寻有效的外语教学途径。

This paper aims at studying how the Japanese learners of English have been influenced by their mother tongue by means of analyzing their written language from the perspective of grammatical categories．Data was collected from the compositions written by the second-year students of English Department at a university．These students had studied English in Japan for about six years before they came to China．Errors found in their essays were thus analyzed，mainly in the six grammatical categories of number，gender，case，person，tense，and word order．Through the elaboration on the differences of the two language types between English and Japanese，this paper attempts to raise EFL teachers' consciousness of interlanguage development of EFL learners in order to better understand the features of the errors committed by EFL learners and to facilitate effective language teaching．The result of the study also provides further materials of language facts for theoretical research in linguistics．