  We calculate the meson correlators in the $\epsilon$-regime of two-flavor
QCD. On a $16^3\times 32$ lattice with $a\sim 0.11$ fm, the lattice simulations
are performed with the dynamical overlap fermions. We reduce the sea quark mass
down to $\sim$ 3 MeV and the valence quark masses are taken in the range 1-4
MeV. The meson correlators in various channels are compared with the
predictions of (partially quenched) chiral perturbation theory (ChPT).
Including the NLO order of the $\epsilon$-expansion, we extract the
leading-order low energy constants of ChPT, the pion decay constant $F$ and the
chiral condensate $\Sigma$, as $F=87.3(5.5)$ MeV and
$\Sigma^{\bar{\mathrm{MS}}}=[237.8(4.0){MeV}]^3$.
