  We use a microscopic three-cluster model with the $\alpha+\alpha+n$
configuration to analyze with astrophysical interests the photodisintegration
cross section of $^9$Be. The valence neutron in $^9$Be is treated in the
molecular orbit model (MO), including continuum states by the box
discretization method. It is shown that good agreement is achieved with the
recently measured B(E1) transition probability from the ground state to the
first 1/2$^+$ state when the box size is enlarged, resulting in reasonable
reproduction of the experimental data for the photodisintegration cross
section. The Coulomb dissociation of $^9$Be is also discussed.
