 The beam is directed towards the Super-Kamiokande far detector located 295 km away in the city of Hida, Gifu prefecture.The properties and composition of the neutrino flux are first measured by a system of near detectors located 280 m from the beam production place at the J-PARC site, and then again in the Super-Kamiokande detector.Comparison of the content of different neutrino flavours in these two locations allows measurement of the oscillations probability on the way between near and far detectors.