  A D0 meson can decay to K+ pi- through doubly Cabibbo-suppressed decay or via
D0-D0bar mixing. With 46.2 fb^{-1} of integrated luminosity collected by Belle,
we have measured the time integrated rate of the wrong-sign process D0 -> K+
pi- relative to that of the Cabibbo-favored process D0 -> K- pi+ to be R_WS =
(0.372 +- 0.025 +0.009/-0.014) % (preliminary). The D0-D0bar mixing parameters
can be derived from the time distribution of the wrong-sign process.
