  We evaluate the corrections of the two-photon exchange (TPE) process on the
$\gamma^* N\Delta$ transition form factors. The contributions of the TPE
process to the $eN\rightarrow e\Delta(1232)\rightarrow eN\pi$ are calculated in
a hadronic model with the inclusion of only the elastic nucleon intermediate
states, to estimate its effects on the multipoles $M^{(3/2)}_{1^+},
E^{(3/2)}_{1^+}, S^{(3/2)}_{1^+}$ at the $\Delta$ peak. We find that TPE
effects on $G^*_M$ is very small. $G^*_E,$ and $ G^*_C$ are also little
affected at small $Q^2 $. For $G^*_E$, the TPE effects reach about $3 - 8\%$
near $Q^2\sim 4$ GeV$^2$, depending on the model, MAID or SAID, used to emulate
the data. For $G^*_C$, the TPE effects decrease rapidly with increasing
$\epsilon$ while growing with increasing $Q^2$ to reach $\sim 6 - 15\%$ with
$Q^2 \sim 4$ GeV$^2$ at $\epsilon = 0.2$. Sizeable TPE corrections to $G^*_E$
and $G^*_C$ found here points to the need of including TPE effects in the
multipole analysis in the region of high $Q^2$ and small $\epsilon$. The TPE
corrections to $R_{EM}$ and $R_{SM}$ obtained in our hadronic calculation are
compared with those obtained in a partonic calculation for moderate momentum
transfer of $2<Q^2<4$ GeV$^2$.
