Temperature dependence of the antiferromagnetic resonance spectrum in a thulium orthoferrite (TmFeO3) poly-crystalline sample was studied by transmission spectroscopy in the frequency range of 0.1–0.75 THz and temperature range of 300–670 K, up to its Néel temperature. We observed quasi-ferromagnetic resonance and the quasi-antiferromagnetic resonance modes. The temperature dependence of the resonance frequencies, linewidths, and amplitudes were extracted. The resonance spectrum of TmFeO3 near its Néel temperature was directly observed and a drastic drop in resonance frequency for both modes was observed.