  The T2K experiment has reported the first observation of the appearance of
electron neutrinos in a muon neutrino beam. The main and irreducible background
to the appearance signal comes from the presence in the neutrino beam of a
small intrinsic component of electron neutrinos originating from muon and kaon
decays. In T2K, this component is expected to represent 1.2% of the total
neutrino flux. A measurement of this component using the near detector (ND280),
located 280 m from the target, is presented. The charged current interactions
of electron neutrinos are selected by combining the particle identification
capabilities of both the time projection chambers and electromagnetic
calorimeters of ND280. The measured ratio between the observed electron
neutrino beam component and the prediction is 1.01+-0.10 providing a direct
confirmation of the neutrino fluxes and neutrino cross section modeling used
for T2K neutrino oscillation analyses. Electron neutrinos coming from muons and
kaons decay are also separately measured, resulting in a ratio with respect to
the prediction of 0.68+-0.30 and 1.10+-0.14, respectively.
