Training qualified teachers is one of the most important factors the quality of education systems. The process of educating pre-service teachers is sine qua non for training qualified teachers. This study aimed to examine lesson study model within the scope of professional development in terms of pre-service teachers. The research adopted a single case study, one of the qualitative research methods. The sample consisted of senior students in Division of Classroom Education (Muş Alparslan University Faculty of Education) in the 2017-2018 academic year. Criterion sampling was used to recruit volunteer pre-service teachers (four males and four females). A curriculum was developed to introduce lesson study model to pre-service teachers. Data were collected with semi-structured interview forms and teacher diaries. Semi-structured interviews were held at three different intervals and in three different contexts: interviews conducted before the curriculum, interviews conducted after the curriculum, and interviews conducted after the implementation. Pre-service teacher diaries were completed each week after the implementation. Data obtained from semi-structured interviews and teacher trainee diaries were analyzed by two different coders by the help of content analysis method. Findings showed that lesson study model made a significant positive contribution to the professional development of pre-service teachers in various aspects such as lesson plan, teaching methods and techniques, and course evaluation. Lesson study model was found to have some limitations; thus, recommendations were provided regarding how to implement the model better.