Self-determination can affect students to have a positive way of thinking and acting, also to make realistic choices so they can make a decision responsibly. This study aimed to develop a questionnaire to measure student self-determination and validate it. This study was conducted in 2019, involved 406 university students as participants consisting of 78 males and 328 females, aged 20-24 years in Universitas Pendidikan Indonesia. This study utilized the quantitative approach as its method and there are 18 questionnaires with a 7-point Likert scale as an answer choice. The data analysis used the Rasch model, "i.e." Winsteps software. Study results show that the Cronbach Alpha value, which measures the interaction between the person and items, is 0.96, which falls into the excellent category of performance. In addition, the Person Reliability of 0.94 demonstrates that the respondents have consistently correctly answered questions, even in the outstanding category. The items in the self-determination questionnaire have high reliability so that they can be used to measure the self-determination of university students.