  We extend the proposal of Berenstein, Maldacena and Nastase to Type IIB
superstring propagating on pp-wave over ${\bf R}^4/{\bf Z}_k$ orbifold. We show
that first-quantized free string theory is described correctly by the large
$N$, fixed gauge coupling limit of ${\cal N}=2$ $[U(N)]^k$ quiver gauge theory.
We propose a precise map between gauge theory operators and string states for
both untwisted and twisted sectors. We also compute leading-order perturbative
correction to the anomalous dimensions of these operators. The result is in
agreement with the value deduced from string energy spectrum, thus
substantiating our proposed operator-state map.
