  We study the direct CP violation induced by inelastic final state interaction
(FSI) rescattering in $D\to\pi\pi$ modes, and find that the resultant CP
asymmetry is about $10^{-4}$ which is larger than $\epsilon'$ in the K-system.
Our estimation is based on well-established theories and experiment measured
data, so there are almost no free parameters except the weak phase
$\delta_{13}$ in the CKM matrix.
