Objective: The objectives of the present study were to develop a tool to assess school-aged children’s handwriting using Rasch analysis, testing the tool’s reliability and validity. Methods: The development of the handwriting evaluation tool proceeded in Four steps namely, construction of assessment items, test for construct validity using Rasch analysis, and test for inter-rater reliability. In the first step, Preliminary items for handwriting evaluation were collected through literature search. In the second step, 17 items were constructed through expert survey, content validity survey and expert review. In the third step, In the final step, testing and scoring methods were determined. data were collected from 326 1st–6th grade children and a handwriting evaluation tool consisting of 16 items was developed based on the Rasch analysis results. Results: The following results were obtained. First, regarding subject fit and item fit examined through Rasch analysis, on the sentences of lower difficulty the number of misfit subjects were 13 and misfit items were reverse and the degree to which lines were smooth, while on the sentences of higher difficulty the number of misfit subjects were 11 and misfit item was the degree to which lines were smooth. Second, regarding item difficulty, the average subject ability was higher than the average item difficulty. The most difficult item was consistency in letter size, while the least difficult item was reverse. Third, the item reliability computed in the Rasch analysis was excellent, ranging from .96–.99, and the subject reliability was acceptable with a range of .69–.70. Conclusion: This study is significant since it is the first to develop a tool that takes the unique features of Hangul (Korean alphabet) into account and objectively assesses school-aged children’s handwriting. We believe the study’s findings will be useful for occupational therapists who assess and treat school-aged children’s major task, handwriting