Objectives: The purpose of this study was to investigate the effects of a spelling intervention program based on morphological awareness on school-age children’s spelling and morphological awareness abilities. Methods: A total of 3 children with spelling difficulties in 3rd to 4th grade were selected. A dictation test tool was applied, focusing on words with aspirated consonants and ‘ㅎ’ (/h/) deletion; and consisting of single words, compound words, and derivative words. A multi-intermittent baseline design methodology including pre-, post-, and maintenance procedures was applied, and the intervention period was 2-3 times a week for 5-6 weeks, for a total of 16 sessions. Results: First, it was found that the spelling intervention effect focusing on aspirated and ‘ㅎ’ deletion of children with spelling difficulties based on morphological awareness ability resulted in improved performance compared to the baseline and was maintained 2 weeks after the intervention. Second, as a result of the spelling intervention based on morphological awareness ability, it was found that the morphological awareness ability of children with poor writing skills improved compared to the baseline and was maintained even 2 weeks after the intervention. Conclusion: The results of this study suggest that morphological awareness-based spelling interventions can be used for evidence-based spelling education for children with spelling difficulties.