This study surveys the factors regarding reading and writing difficulties in children with attentiondeficit hyperactivity disorder (ADHD) and uses these results to provide support. We conducted surveys on 16 elementary school children from 3rd to 6th grades who were diagnosed with ADHD by a physician based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). We conducted a Hiragana reading test, a Kanji reading and writing test, and a visual perception test on the subject children. We requested that the parents of the children complete a reading and writing symptom checklist, the Developmental Coordination Disorder Questionnaire (DCDQ), the Strength and Difficulties Questionnaire (SDQ), the ADHD-Rating Scale (ADHD-RS), and the Autism-Spectrum Quotient (AQ). We conducted a multiple regression analysis using the Kanji reading and writing test as the dependent variable. Results revealed that the positional task score in the visual perception test was a factor that influences Kanji writing. Meanwhile, gender, reading-related items on the reading and writing symptom checklist, and performance such as misreading of hiragana were factors that influenced Kanji reading. Based on the results, we suggested that when teaching Kanji writing, children's visual cognition ability should be assessed, and ways to incorporate learning methods that supplement visual perception, such as color masses and electronic learning materials, should be devised. When teaching reading, we suggest using teaching materials that present not only text but also audio as needed, and support the awareness of parents.