  One of physics goals of the NA61/SHINE experiment is a measurement of hadron
production cross sections from proton-Carbon interactions at 31GeV/c for the
T2K experiment at J-PARC. A precise knowledge of differential cross sections
for pion and kaon production is of importance for improving the accuracy of
neutrino flux simulations. The NA61 detector has a large angular acceptance,
full coverage of the T2K phase space region, and good particle identification.
In this work the analyses of negatively charged pion production are presented.
Two different methods of negative pion selection and corrections for detector
effects are discussed. Finally, preliminary dn/dp distributions of negatively
charged pion in p+C interactions at 31 GeV/c are presented.
