  We study measurement of the CP property of the Higgs boson at a photon linear
collider. One method where we take advantage of interference between
Higgs-production and background amplitudes is proposed. A broad peak of the
photon energy spectrum is helpful in observing the energy dependence of the
interference effects. Numerical results for the process $\gamma \gamma \to t
\bar{t}$ are shown as an example.
