OBJECTIVES: Reading and writing skills are important for hearing-impaired children since these skills help them to develop their language skills, but the prevalence of reading/writing difficulties and its effects on language development aspects among them are unclear. In this study, we identified language development features and demographic factors of Japanese hearing-impaired children diagnosed as having reading/writing difficulties. METHODS: We analyzed data from a total of 546 sever-to-profound pre-school and elementary school hearing-impaired children for this study. Children with reading/writing difficulties (Group A) were defined as children obtaining low scores (-1.5 SD compared to others in the same grade) in the Screening Test of Reading and Writing for Japanese Primary School Children (STRAW), and we compared other language development features (communication ability, vocabulary, syntax and academic achievement) and demographic factors to those of hearing-impaired children with normal reading and writing skills (Group B). We assessed language development domains as outcomes using the Assessment of Language Development for Japanese Children (ALADJIN) package, and analyzed the results stratified by age groups (5-6, 7-8, 9-10, and 11-12 years) using multiple regression analyses. RESULTS: The prevalence of reading/writing difficulties was 20.1% among the participants. Almost all point estimates in each language development domain showed better odds ratios (OR) except Criterion Referenced Test -II (CRT-II) mathematics in 11- to 12-year-olds in fully-adjusted models. Among 9- to 10-year-olds, the ORs (95% confidence interval) for fair academic achievement measured by CRT-II were 2.60 (1.09-6.20) for Japanese and 3.02 (1.29-7.11) for mathematics in Group B, even after adjusting for possible confounding factors. CONCLUSIONS: Reading and writing are important for language development of hearing-impaired children, especially for academic achievement during the middle phase of elementary school. Screening for reading/writing difficulties is important for appropriate intervention and to prevent language and academic delays among hearing-impaired children.