Purpose: The aim of the current research was to identify the obstacles to implementing Lesson Study in primary schools of education in Ardabil.Method: To achieve the aim, the case study strategy was used, with the qualitative data being studied first, and on the basis of which the quantitative research was conducted. The study population were 1957 primary school teachers in Ardabil city. In the quantitative side, 298 people were selected through simple random sampling. In the qualitative part, 11 members were selected using purposive sampling, and in-depth interviews were conducted with them. To collect qualitative data, unstructured an interview was conducted which was validated based on triangulation and member checking methods. On the other hand, the tool for the quantitative phase was researcher-designed questionnaire the reliability of which was 0.79. Inductive content analysis, through open coding, was used for analyzing the qualitative data; and the PLS software was used for analyzing the quantitative data.Finding: The findings showed that organizational factors (including centralized organizational structure, organizational culture, leadership style, technology, internal processes) and personal factors (including teachers, lack of commitment of teachers and their personalities) are factors that hinder the implementation of lesson-study in schools. This research also indicated that among the aforementioned factors, most influencing factor hindering lesson study was focused organizational structure and the least influencing factor was teacher information.