  We investigate target mass effects in the unpolarized virtual photon
structure functions $F_2^\gamma(x,Q^2,P^2)$ and $F_L^\gamma(x,Q^2,P^2)$ in
perturbative QCD for the kinematical region $\Lambda^2 \ll P^2 \ll Q^2$, where
$-Q^2(-P^2)$ is the mass squared of the probe (target) photon and $\Lambda$ is
the QCD scale parameter. We obtain the Nachtmann moments for the structure
functions and then, by inverting the moments, we get the expressions in closed
form for $F_2^\gamma(x,Q^2,P^2)$ up to the next-to-next-to-leading order and
for $F_L^\gamma(x,Q^2,P^2)$ up to the next-to-leading order, both of which
include the target mass corrections. Numerical analysis exhibits that target
mass effects appear at large $x$ and become sizable near $x_{\rm
max}(=1/(1+\frac{P^2}{Q^2}))$, the maximal value of $x$, as the ratio $P^2/Q^2$
increases.
