  In this paper, we introduce a notion of ampleness of a group action $G$ on a
right noetherian graded algebra $A$, and show that it is strongly related to
the notion of $A^G$ to be a graded isolated singularity introduced by the
second author of this paper. Moreover, if $S$ is a noetherian AS-regular
algebra and $G$ is a finite ample group acting on $S$, then we will show that
${\mathcal D}^b(\operatorname{tails} S^G)\cong {\cal D}^b(\operatorname{mod}
\nabla S*G)$ where $\nabla S$ is the Beilinson algebra of $S$. We will also
explicitly calculate a quiver $Q_{S, G}$ such that ${\mathcal
D}^b(\operatorname{tails} S^G)\cong {\mathcal D}^b(\operatorname{mod} kQ_{S,
G})$ when $S$ is of dimension 2.
