  We study the entropy of extremal warped black hole obtained from the
topologically massive gravity with a negative cosmological constant of
$\Lambda=-1/l^2$. We compare the entropy $S_e=\pi \alpha/3G$ from the Wald
formalism with $S_w=\pi l u /3G$ from the entropy function approach. These are
the same if $\alpha=l u$. Also we obtain the same Cardy formula when $J_e= l^3
q$ with $J_e$ the angular momentum and $q$ the conserved quantity.
