  The overabundance of the red and massive candidate galaxies observed by the
James Webb Space Telescope (JWST) implies efficient structure formation or
large star formation efficiency at high redshift $z\sim 10$. In the scenario of
a low or moderate star formation efficiency, because massive neutrinos tend to
suppress the growth of structure of the universe, the JWST observation tightens
the upper bound of the neutrino masses. Assuming $\Lambda$ cold dark matter
cosmology and a star formation efficiency $ \in [0.05, 0.3]$ (flat prior), we
perform joint analyses of Planck+JWST and Planck+BAO+JWST, and obtain improved
constraints $\sum m_\nu < 0.196\,\mathrm{eV}$ and $\sum m_\nu <
0.111\,\mathrm{eV}$ at 95% confidence level, respectively. Based on the above
assumptions, the inverted mass ordering, which implies $\sum m_\nu\geq
0.1\mathrm{eV}$, is excluded by Planck+BAO+JWST at 92.7% confidence level.
