The study aimed to investigate the effects of Lesson Study on the self-efficacy beliefs of pre-service kindergarten teachers. A quasi-experimental design with two parallel groups was used. The sample consisted of 49 students divided into a control group (27) and an experimental group (22). The pre-service kindergarten teachers in the experimental group followed an adjusted Lesson Study design, while the control group followed the traditional way of pre-service teaching practice. Findings indicate that there was no significant difference in teacher self-efficacy total scores between the groups, but there was a significant difference in the self-reported competence to effectively teach mathematics lessons and ability to get and keep pupils motivated.