This research aims to develop a test instrument that measures the statistical reasoning ability of teacher candidate students. Statistical reasoning is the main goal in learning statistics, where more attention is give to descriptive statistics concepts. However, assessment of the concept of descriptive statistics has not been fully considered in education in Indonesia, especially in terms of summative and formative assessments oriented to the development of student competencies. There are relatively few statistical reasoning ability test instruments in the context of teacher candidate students. Therefore, this research intends to develop a statistical reasoning ability test instrument based on the framework of Chan & Ismail in the context of prospective teacher students. The development model used is a 4D model: Define, Design, Develop, and Disseminate. Information collection was carried out by validating test instruments by 3 validators of Mathematics and Statistics Education lecturers. The results of the study stated that the instrument developed was declared valid and could be used to measure the statistical reasoning ability of teacher candidate students.