<p>We have developed LiGaO₂ nanoparticle-loaded plastic scintillators. The particle size of LiGaO₂ nanoparticles was 25–200&#xa0;nm. In the horizontal direction, no aggregation of the nanoparticles in the plastic scintillators was observed at low nanoparticle concentration, whereas aggregation of nanoparticles was observed at high nanoparticle concentration. The vertical dispersion of nanoparticles in the plastic scintillators was inhomogeneous with agglomerations of the nanoparticles at the lower part of the plastic scintillators. In the X-ray-induced radioluminescence (XRL) spectrum, a peak at 383&#xa0;nm was observed for the LiGaO₂ nanoparticles and is attributed to the charge transfer transition from Ga²⁺ to O⁻. In the XRL spectra of the plastic scintillators loaded with the LiGaO₂ nanoparticles, a peak at 420&#xa0;nm was observed and is attributed to 1,4-bis[2–(5–phenyloxazolyl)]benzene included as the organic phosphor. The scintillation light yields under neutron irradiation of the plastic scintillators loaded with LiGaO₂ nanoparticles were 1880–2270 photons/neutron at the loading amounts of 5–25 wt% with the highest scintillation light yield at 20 wt%. The scintillation light yields are significantly higher than that of a ¹⁰B–loaded plastic scintillators (EJ-254) of 800 photons/neutron, which is a commercially available plastic scintillator for neutron detection.</p>