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We study cosmic-ray anomaly observed by PAMELA based on E_6 inspired extraU(1) model with S_4 flavor symmetry. In our model, the lightest flavon has verylong lifetime of O(10^18) second which is longer than the age of the universe,but not long enough to explain the PAMELA result O(10^26) sec. Such a situationcould be avoidable by considering that the flavon is not the dominant componentof dark matters. However non-thermalizing the flavon is needed to obtain properrelic density. This relates reheating temperature of the universe with seesawmass scale. If we assume this flavon is a particle decaying into positron (orelectron), the seesaw mass scale is constrained by reheating temperature. Thuswe find an interesting result that the allowed region is around O(10^12) GeV,which is consistent with our original result.

Seesaw Mechanism Confronting PAMELA in S_4 Flavor Symmetric Extra U(1) Model