Waine, Broomfield, Banham, & Espie (2009) developed and validated the Metacognitions Questionnaire-Insomnia (MCQ-I) to assess metacognition about sleep, which was hypothesized to have a two-factor structure consisting of metacognitive belief about sleep, and metacognitive plans about sleep. However, it is unclear if the MCQ-I reflects metacognition about sleep as hypothesized because no item analysis or factor analysis was conducted. The present study was designed to develop a short version of MCQ-I using selected items and investigate its reliability and validity. A cross-sectional survey using the MCQ-I was conducted with undergraduates (N=330) and 27 patients with chronic insomnia disorder. Results of factor analysis and item analysis of their responses indicated that MCQ-I has a two-factor structure as hypothesized, and 25 items had high internal consistency. Moreover, the MCQ-I-25 was correlated with metacognition about worry, comprehensive dimensions of cognitive arousal, and sleep disturbances. Furthermore, the MCQ-I-25 score was higher in insomnia patients than healthy students. These results suggest that MCQ-I-25 reflects metacognition about sleep and could predict cognitive arousal and insomnia.