We investigate target mass effects in the unpolarized virtual photonstructure functions $F_2^\gamma(x,Q^2,P^2)$ and $F_L^\gamma(x,Q^2,P^2)$ inperturbative 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 $\Lambda$ isthe QCD scale parameter. We obtain the Nachtmann moments for the structurefunctions and then, by inverting the moments, we get the expressions in closedform for $F_2^\gamma(x,Q^2,P^2)$ up to the next-to-next-to-leading order andfor $F_L^\gamma(x,Q^2,P^2)$ up to the next-to-leading order, both of whichinclude the target mass corrections. Numerical analysis exhibits that targetmass effects appear at large $x$ and become sizable near $x_{\rmmax}(=1/(1+\frac{P^2}{Q^2}))$, the maximal value of $x$, as the ratio $P^2/Q^2$increases.
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