An accelerator based Boron Neutron Capture Therapy (BNCT) is a new trend for radiation therapy of cancer. In the Ibaraki neutron medical research center, a project to develop an accelerator based BNCT system called “iBNCT” (Ibaraki, BNCT) is in progress. In this paper, the accelerator system, which output proton beam with the beam energy of 8 MeV and beam current of 2.1 mA DC equivalent, will be introduced.