In our institute, heavy ion medical accelerator in Chiba (HIMAC) completed to be constructed October, 1994. Next year, we started to treat head & neck cancer firstly as a pilot study using carbon beam. Following the observation on the expected reaction of skin and mucosa membrane, we opened the protocol for lung cancer entitled "A phase I/II and II clinical trials of heavy iron particle radiotherapy for non-small cell carcinoma of the lung". Since then, Cabon beam possessing the well-balanced dual actions on cancer: efficient dose-localization and high RBE was given to 25 inoperable patients with stage 1 and 3 patients with stage IIIA as preoperative radiotherapy. The dose was raising from 59.4GyE, 64.5GyE and 72GyE by 10%. Tumor control of the patients who elapsed more than 6 months was evaluated in two of 4 patients (50%) given 59.4GyE, one of 4 (75%) given 64.5GyE and all of 17 (100%) given 72GyE. It appeared to be dose dependent. On the other hand, two of 28 patients (7%) showed acute radiation pneumonia treated with steroid hormone. However, the late effect of the lung was weaken with slight radiographic changes and with no manifestations. Now that heavy ion particle radiotherapy for lung cancer was revealed to be safe, we intend to attain the tumor control compatible with that of surgery.