  Several investigations show that in a very small length scale there exists
corrections to the entropy of black hole horizon. Due to fluctuations of the
background metric and the external fields the action incorporates corrections.
In the low energy regime, the one loop effective action in four dimensions
leads to trace anomaly. We start from the Noether current corresponding to the
Einstein-Hilbert plus the one loop effective action to calculate the charge for
the diffeomorphisms which preserve the Killing horizon structure. Then a
bracket among the charges is calculated. We show that the Fourier modes of the
bracket is exactly similar to Virasoro algebra. Then using Cardy formula the
entropy is evaluated. Finally, the explicit terms of the entropy expression is
calculated for a classical background. It turns out that the usual expression
for entropy; i.e. the Bekenstein-Hawking form, is not modified.
