  We discuss the possibility of constraining or discovering the non-standard
neutrino physics beyond the standard model with future long baseline neutrino
oscillation experiments. Among very many possible experimental set up we
discuss neutrino factory and T2KK, in which two detector setting may be useful
to achieve the goal. In particular, neutrino factory with two detectors at
baselines of 3000 km and 7000 km have a great sensitivity to non-standard
interaction (NSI) and solve the $\theta_{13}$-NSI confusion problem.
