  The light scalar meson spectrum is studied using the improved ladder QCD with
the UA(1) breaking Kobayashi-Maskawa-'t Hooft interaction by solving the
Schwinger-Dyson and Bethe-Salpeter equations. The dynamically generated
momentum-dependent quark mass is large enough in the low momentum region to
give rise to the spontaneous breaking of chiral symmetry. Due to the large
dynamical quark mass, the scalar mesons become the q bar{q} bound states. Since
the parameters have been all fixed to reproduce the light pseudoscalar meson
masses and the decay constant, there is no free parameter in the calculation of
the scalar mesons. We obtain $M_{sigma} = 667$ MeV, $M_{a_0} = 942$ MeV and
$M_{f_0} = 1336$ MeV. They are in good agreement with the observed masses of
$sigma(600)$, $a_0(980)$ and $f_0(1370)$, respectively. We therefore conclude
that these states are the members of the light scalar meson nonet. The mass of
$K_0^{*}$ is obtained between that of $a_0$ and $f_0$ and the corresponding
state is not observed experimentally. We also find that the strangeness content
in the $sigma$ meson is about 5%.
