The accelerator complex consists of the following accelerators:

• A 400-MeV normal-conducting Linac,
  
• A 600-MeV superconducting Linac to increase the energy from 400 to 600 MeV,
• A 3-GeV rapid-cycling synchrotron (RCS), which provides proton beams at 333 µA (1 MW),
  and
• A 50-GeV synchrotron, which provides proton beams at 15µA(0.75 MW).

The use of the RCS for the pulsed spallation neutron source is a unique accelerator scheme. This became possible by innovating the RF accelerating system for the synchrotron: the RF cavity, loaded with the magnetic alloy, could generate the accelerating field gradient by a factor of two to five higher than that the conventional ferrite-loaded cavities. The high-quality linac beams (small, parallel beams) are required for the RCS injection. For this purpose, the 3-MeV RFQ linac is installed with the pi-mode stabilizing loops, which make the RFQ field purely quadratic. The following 50-MeV drift-tube linac was installed with very compact electromagnets fabricated with a combination of the electroforming and the wire-cutting technologies. In this way, J-PARC many new technologies have been invented and developed for the accelerator.