We have been demonstrating natural formation and characterization of InGaAs strained quantum wire (QWR) structures on coherent GaAs multiatomic steps grown by metalorganic vapor phase epitaxy (MOVPE). In this paper, we report on the optical properties of InGaAs QWRs. First, photoluminescence (PL) and photoluminescence excitation (PLE) spectra were taken at 77 K. PLE spectra showed the polarization anisotropy for excitation light with electric field parallel or perpendicular to the QWRs. Next, we measured the PL of InGaAs QWRs on GaAs multiatomic steps at 4.2 K, in magnetic fields, to examine the lateral confinement. It was found that the diamagnetic coefficient is 16 μeV/T 2, and is much smaller than that of quantum well (QWL) on singular (001) GaAs substrates (45 μeV/T 2), which suggests the presence of lateral confinement. We also succeeded for the first time in the pulsed laser operation of InGaAs QWRs on GaAs multiatomic steps at 77 K by current injection.