  We discuss a neutrino mass model based on the S_4 flavor symmetry within the
minimal seesaw framework, in which only two right-handed neutrinos are
introduced and transform as 2 under S_4. Although the model contains less free
parameters compared to the typical seesaw models, it provides a successful
description of the observed neutrino parameters, and in particular, a nearly
tri-bimaximal mixing pattern can be naturally accommodated. In addition, the
heavy right-handed neutrino masses are found to be non-degenerate, while only
the normal hierarchical mass spectrum is compatible with experiments for light
neutrinos.
