  We study general constraints on spontaneous R-symmetry breaking models coming
from the cosmological effects of the pseudo Nambu-Goldstone bosons, R-axions.
They are substantially produced in the early Universe and may cause several
cosmological problems. We focus on relatively long-lived R-axions and find that
in a wide range of parameter space, models are severely constrained. In
particular, R-axions with mass less than 1 MeV are generally ruled out for
relatively high reheating temperature, $T_R>10$ GeV.
