Proton beam therapy (PBT) is a type of radiation therapy using positively-charged particles, i. e. protons, for the treatment of malignant tumor, and is also an advanced high-technology radiotherapy using large-scale equipment, such as a synchrotron accelerator or isocentric rotational gantry systems. Since a proton beam has advantageous physical properties, i. e. Bragg peak peculiar to a charged particle beam, in formation of dose distribution as compared with mega voltage x-rays in a conventional radiotherapy, a delivery of a conformal high dose to a localized target volume is easily attained, and both improvement in local control rate and reduction of normal tissue impairment can be expected as the result. PBT is adopted mainly as a radical treatment for patients with early-stage or locally-advanced prostatic cancer, hepatocellular carcinoma, non-small cell lung cancer, or head & neck malignant tumor. Moreover, the benefits of PBT may be shared not only with a pediatric patient who is easily injured and growth disturbed by even low-level irradiation of normal tissues/organs and also with an inoperable elderly patient with several medical complications. Insurance coverage in connection with its use for certain diseases is recently under discussion. This paper describes the actual status of PBT including present activities and clinical experiences at Shizuoka Cancer Center about 5 years from the start of PBT.