A magneto-optical survey was conducted for HgCr2O4 powder samples under pulsed high magnetic fields of up to 55 T. Intensity changes in magnetic fields observed for the exciton-magnon-phonon optical transition spectra coincide well with those of magnetization, lattice distortion from X-ray diffraction, and electron-magnetic resonances. The last-ordered phase was detected prior to the fully polarized magnetic phase, similarly to the other chromium spinel oxide, ZnCr2O4 and CdCr2O4.