In the shielding calculation of the nuclear fusion reactor, neutron and photon transport calculations have been performed by using three dimensional Monte Carlo calculation code MCNP. Recent applications with MCNP are reported in the shielding calculations of the nuclear fusion reactor. CAD/MCNP conversion codes have been developed, and MCNP calculation geometry data are automatically created by CAD/MCNP conversion codes. Details and application results are reported on the CAD/MCNP conversion code. By modifying the MCNP code and nuclear data library, the effective dose rates after reactor shutdown have been calculated with high accuracy. The calculation method and the application results are reported on the effective dose rates after shutdown.