We have developed an optical pumping NMR system for semiconductors as an effective nuclear spin polarizer for a solid-state NMR quantum computer. The system was successfully applied to enhance 31P nuclear spin polarization in InP doped with Fe, and the enhancement of the 31P NMR signal by more than two orders of magnitude was achieved. We also observed the strong dependences of the enhancement on the helicity and the photon energy of incident light. The most effective enhancement was achieved with the helicity σ+ and photon energy smaller than the bandgap by 10∼15 meV.