Belief is considered to be one of the important factors that influences pedagogy. In inquiry-based teaching (henceforth, IBT), a student-centered pedagogy, instructions of teacher are of particular importance to facilitate students in active and extended learning. Studies found that instructional practices in teaching vary from teacher to teacher. Belief might be one of the factors for such variation. Several others studies explored the relation between the belief and practice, but no research has been conducted so far in Bangladesh regarding secondary science teachers' beliefs and practices in IBT. The problem discussed here is, therefore, whether there is any consistence between belief and IBT and challenges to implement IBT. The aim of the research was to explore if teachers' beliefs on IBT influences actual classroom practice of science teachers and associated challenges. For this, a qualitative approach is used. To collect data, four teachers of Physics, Chemistry, Botany, and Zoology subjects at secondary level were conveniently selected. Firstly, classroom observation with a belief schedule was used to understand the actual practice of teachers. Next, the teachers were provided with a belief schedule where teachers beliefs were reflected. A semi-structured interview was also used to collect data from science teachers. Result shows that the teachers who believed science learning was associated with inquiry-based scientific practices, imparted it in their practice and vice versa. Large class size, interest, and abilities of students, insufficient time for preparation are the major constraints found in this study. Contents of the textbook are not in line with the curriculum was another major challenge. Mitigation of such contextual constrains and the adoption of inquiry-based curriculum should come along with the adjustment of content in the textbook. At the same time, it may be useful to unpack the beliefs of teachers and reflect on what own beliefs mean for practice.