In the study, background factors involved in Kanji writing di culty in Japanese second to sixth graders (N=1398) were investigated. Children with both Kanji reading and writing di culties were grouped into those with low vocabulary attainment (Group A) and those without it (Group B). Children with only Kanji writing di culty were classi ed into those with low vocabulary attainment (Group C) and those without it (Group D). Because of the small number of children, Group C was removed from the analysis. In Group A's third and fourth graders, the contribution of verbal working memory was observed by employing multiple logistic analysis; Group A's odds ratio values were larger than those of Groups B and D. In Group B, the contribution of uent Hiragana reading was observed, which was not observed in Group D. ese results reveal that background factors involved in Kanji writing di culty might depend on a combination of Kanji reading di culty and low vocabulary attainment.