We discuss the CP-odd Higgs boson production through the two-photon processes in $e\gamma$ collisions. First we briefly review the Standard Model Higgs boson production in $e\gamma$ collisions, with special attention to transition form factor and differential production cross section. We then study the production of the CP-odd Higgs boson $A^0$ which appears in the extended Higgs sector such as the Minimal Supersymmetric Standard Model (MSSM) or in the Two-Higgs Doublet Models (2HDM).The electroweak one-loop contributions to the scattering amplitude for $e\gamma\rightarrow eA^0$ as well as the transition form factor are calculated and expressed in an analytical form. We found that one-loop contribution only comes from top-quark loops. There are no contributions from W-boson loop nor from stop loop. Numerical analysis for the production cross section is presented. It turns out that the $\gamma^*\gamma$-fusion is far more dominant over the $Z^*\gamma$-fusion.