The positive-ion based NBI system for JT-60 began operation in 1986 with hydrogen beam, and had injected the neutral beam power of 27 MW at 75 keV. The beam species has been changed to deuterium through changing the ion sources and beam-line components in 1991. The NBI has injected a deuterium beam of 40 MW at 96 keV in 1996. In 2000, the computer control system for the beam operation has been changed from a mini-computer to a workstation system in order to match a great variety of beam injection parameters, and the operation capability has greatly improved.