  We present a measurement of CP-violation parameters in the B0 -> KsKsKs decay
based on a sample of 275 x 10^6 BBbar pairs collected at the Upsilon(4S)
resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider.
One neutral B meson is fully reconstructed in the decay B0 -> KsKsKs, and the
flavor of the accompanying B meson is identified from its decay products.
CP-violation parameters are obtained from the asymmetry in the distributions of
the proper-time interval between the two B decays: S = +1.26 +/- 0.68(stat) +/-
0.20(syst) and A = +0.54 +/- 0.34(stat) +/- 0.09(syst).
