  We study the possibility of measuring T (time reversal) violation in a future
long baseline neutrino oscillation experiment. By assuming a neutrino factory
as a staging scenario of a muon collider at the J-PARC site, we find that the
${\nu}_e \to {\nu}_{\mu}$ oscillation probabilities can be measured with a good
accuracy at the Hyper-Kamiokande detector. By comparing with the probability of
the time-reversal process, ${\nu}_{\mu} \to {\nu}_e$, measured at the T2K/T2HK
experiments, one can determine the CP phase $\delta$ in the neutrino mixing
matrix if $| \sin(\delta)|$ is large enough. The determination of $\delta$ can
be made with poor knowledge of the matter density of the earth as T violation
is almost insensitive to the matter effects. The comparison of CP and
T-violation measurements, ${\it \`a\ la}$ the CPT theorem, provides us with a
non-trivial check of the three neutrino paradigm based on the quantum field
theory.
