Purpose: The aim of this study was to develop a Korean version of Night Eating Questionnaire (KNEQ) and test its psychometricproperties and evaluate items according to item response theory. Methods: The 14-item NEQ as a measure of severity of the nighteating syndrome was translated into Korean, and then this KNEQ was evaluated. A total of 1171 participants aged 20 to 50 completedthe KNEQ on the Internet. To test reliability and validity, Cronbach’s alpha, correlation, simple regression, and factor analysiswere used. Each item was analyzed according to Rasch-Andrich rating scale model and item difficulty, discrimination, infit/outfit,and point measure correlation were evaluated. Results: Construct validity was evident. Cronbach’s alpha was .78. The items of eveninghyperphagia and nocturnal ingestion showed high ability in discriminating people with night eating syndrome, while items ofmorning anorexia and mood/sleep provided relatively little information. The results of item analysis showed that item2 and item7needed to be revised to improve the reliability of KNEQ. Conclusion: KNEQ is an appropriate instrument to measure severity ofnight eating syndrome with good validity and reliability. However, further studies are needed to find cut-off scores to screen personswith night eating syndrome.