  We report improved measurements of time-dependent CP violation parameters for
B^0(\bar{B}^0) -> psi(2S) K_S. This analysis is based on a data sample of
657x10^6 BBbar pairs collected at the Y(4S) resonance with the Belle detector
at the KEKB energy-asymmetric e+e- collider. We fully reconstruct one neutral B
meson in the psi(2S) K_S CP-eigenstate decay channel, and the flavor of the
accompanying B meson is identified to be either B^0 or \bar{B}^0 from its decay
products. CP violation parameters are obtained from the asymmetries in the
distributions of the proper-time intervals between the two B decays:
  S (psi(2S) K_S) = +0.72 +/- 0.09(stat) +/- 0.03(syst),
  A (psi(2S) K_S) = +0.04 +/- 0.07(stat) +/- 0.05(syst).
  These results are in agreement with results from measurements of B^0 -> J/psi
K^0.
