Ebara, Y. Kumata, Y. Miyashita, T. Nakajima, Nakajima, S. Tsurudome, T. Tsutsui, H. Yoshida, J. JACoW Publishing Geneva, Switzerland 2673-5482 978-3-95450-212-7 10.18429/JACoW-CYCLOTRONS2022-WEBO04 English 187-190 cyclotron extraction proton MMI operation Contribution to a conference proceedings 2023 2023-10 https://doi.org/10.18429/JACoW-CYCLOTRONS2022-WEBO04 https://jacow.org/cyclotrons2022/papers/webo04.pdf A 230 MeV superconducting AVF cyclotron SC230 is developed by Sumitomo Heavy Industries, Ltd. This is the world’s smallest isochronous cyclotron for proton therapy, and its weight is 65 tons, which is 0.3 times that of our previous cyclotron model. The size is reduced by generating high magnetic fields using NbTi supercon-ducting coils cooled without cryogen. In addition, this cyclotron features the maximum beam current >1 uA and low power consumption <200 kW. The beam-commissioning test started at the end of 2020, the first extracted beam was observed in July 2021, and the basic performance of the beam was measured. The processes and results of the beam commissioning are reported.