  A model of natural inflation with an effectively trans-Planckian decay
constant can be easily achieved by the "phase locking" mechanism while keeping
field values in the effective field theory within the Planck scale. We give
detailed description of "phase locked" inflation based on this mechanism. We
also construct supersymmetric natural inflation based on this mechanism and
show that the model is consistent with low scale supersymmetry. We also
investigate couplings of the inflaton with the minimal supersymmetric standard
model to achieve an appropriate reheating process. Interestingly, in a certain
class of models, we find that the inflation scale is related to the mass of the
right-handed neutrino in a consistent way with the seesaw mechanism.
