  We study valence fluctuations at finite temperatures in the extended periodic
Anderson model, where the Coulomb interaction between conduction and localized
$f$-electrons is taken into account, using dynamical mean-field theory combined
with the continuous-time quantum Monte Carlo (CT-QMC) method. The valence
transition with the hysteresis is clearly found, indicating the first-order
phase transition between the Kondo and mixed-valence states. We demonstrate
that spin correlation rapidly develops when the system approaches the valence
transition point. The comparison of the impurity solvers, %: the CT-QMC,
non-crossing approximation, and one-crossing approximation, is also addressed.
