In this study, it was done textbook analysis due to find out the learning process of conditional expression of Korean Japanese learner from angle of external factor for textbook of Japanese which using at High school Japanese education field in Korea.
As a result, there were the first thing is that conditional expression at the textbook of High school Japanese is handled fragmentarily and a tendency to repetitively use the same sentence or tendency to bias to one usage by type. Regarding the format, in all the textbooks, it was most concerned about the ‘To’ format among the 4 types. Regarding the handling of each type, the 'To' format has many descriptions about showing the way, the ‘Ba’ and ‘Tara’ forms are overwhelmingly idiomatic expressions, and the ‘Nara’ form has many expressions representing the subject.
In this way, from the textbook which prefers a certain usage, the Korean Japanese learner of high school can not exclude the possibility of inputting the conditional expression by being inclined to any one expression in all usage. However, because the format and usage of condition expressions are not the same according to the textbooks, the learner is prevented from learning the condition expressions in a balanced manner depending on which textbook is used. In other words, we found that there is a big difference in the input of learners' knowledge according to the textbooks used at school.
In addition, reflecting the fact that condition expressions are difficult to learn, it has been found that many usages were not divided in terms of the expression ‘To, Ba, Tara, Nara’ in high school Japanese language education.