  The Tokai-to-Kamioka (T2K) neutrino experiment measures neutrino oscillations
by using an almost pure muon neutrino beam produced at the J-PARC accelerator
facility. The T2K muon monitor was installed to measure the direction and
stability of the muon beam which is produced together with the muon neutrino
beam. The systematic error in the muon beam direction measurement was
estimated, using data and MC simulation, to be 0.28 mrad. During beam
operation, the proton beam has been controlled using measurements from the muon
monitor and the direction of the neutrino beam has been tuned to within 0.3
mrad with respect to the designed beam-axis. In order to understand the muon
beam properties,measurement of the absolute muon yield at the muon monitor was
conducted with an emulsion detector. The number of muon tracks was measured to
be $(4.06\pm0.05)\times10^4$ cm$^{-2}$ normalized with $4\times10^{11}$ protons
on target with 250 kA horn operation. The result is in agreement with the
prediction which is corrected based on hadron production data.
