This study aimed to investigate the effects of static stretching of the calf muscle on ankle position sense and dynamic balance ability following microwave diathermy. Participants were 28 healthy young students in their 20 s, who were divided into a microwave diathermy stretching group (MSG) and a stretching group (SG). A microwave was emitted to the calf muscle area to participants in the MSG. Static stretching was performed by standing on a quadriceps board for 15 minutes. The angle of the wedge was set to a range of 15–25°, representing a level of pain and discomfort allowed by the subjects. Before and after intervention, ankle dorsi-plantar flexion joint position sense (JPS) and dynamic balance ability were measured. The group source affected JPS error of dorsi-plantar flexion (p < 0.05) and JPS error increased with the SG more than the MSG. There was an increase in the dynamic balance score in both groups after the intervention compared to before the intervention. Microwave therapy prior to stretching can preserve JPS and balance ability, thereby reducing the risk of injuries from activities after stretching.