Even though dynamic geometry software (DGS) is becoming an emergent instructional tool for mathematics teachers, many teachers are still in the process of consideration about whether to use it. In order to encourage teachers to use DGS, this study seeks to discover mathematics teachers' salient beliefs about the use of DGS in mathematics class. The theory of planned behaviour serves as the theoretical framework for understanding teachers' intentions to use DGS. Thirty mathematics teachers who have knowledge of and experience using DGS were invited to fill out an online survey. Content analysis of teachers' responses was analysed using the theory of planned behaviour. The behavioural, normative and control beliefs of mathematics teachers using DGS in class were identified. These noticeable beliefs of teachers may be used to create conditions for teachers to successfully integrate this new tool in mathematics class.