  The lifetimes of charmed mesons have been measured using 11.1fb$^{-1} of data
collected with the Belle detector at KEKB. Each candidate is fully
reconstructed to identify the flavor of the charmed meson. The lifetimes are
measured to be $\tau(D^0)=(414.5\pm1.7)$ fs, $\tau(D^+)=(1029\pm12)$ fs and
$\tau(D_s^+)=(488.4^{+7.8}_{-7.7})$ fs, where the error is statistical only.
The mixing parameter $y_{CP}$ is also measured to be
$y_{CP}=(1.16^{+1.67}_{-1.65}(stat.))%$ through the lifetime difference of
$D^0$ mesons decaying into CP-mixed states and CP eigenstates.
