In 2019, our facility introduced robot-assisted surgery for mediastinal tumors using da Vinci Si, which was upgrade to da Vinci X and Xi in 2021. Initially, the unilateral thoracic cavity approach was used for robot-assisted surgeries. The unilateral approach has the advantage of facilitating the anatomical recognition of either the left or right side, with the side used selected depending on the location of the lesion. Notably, challenges such as difficulty in recognizing objects were still encountered. To compensate for these shortcomings, our hospital introduced robotic subxiphoid-optical thymectomy, a subxiphoid approach, which has been used for all robot-assisted mediastinal tumor surgeries since its introduction under the guidance of Kyoto Prefectural University of Medicine. Additionally, extended thymectomy, which has been covered by insurance since 2020 and used as the standard surgical procedure for robot-assisted mediastinal tumor surgery at our department, can be performed using the same approach.