  We present a measurement of the unitarity triangle angle phi_3 using a Dalitz
plot analysis of the K0_S pi+ pi- decay of the neutral D meson from the B+- ->
D(*)K(*)+- process. The method employs the interference between D0 and D0bar to
extract the angle phi_3, strong phase Delta and the ratio r of suppressed and
allowed amplitudes. We apply this method to a 357 fb-1 data sample collected by
the Belle experiment. The analysis uses three modes: B+ -> DK+, B+ -> D*K+ with
D* -> Dpi0, and B+ -> DK*+ with K*+ -> K0_S pi+, as well as the corresponding
charge-conjugate modes. From a combined maximum likelihood fit to the three
modes, we obtain phi_3=53+15-18(stat)+-3(syst)+-9(model) degrees. The
corresponding two standard deviation interval is 8<phi_3<111 degrees.
