The effects of ⁶⁰Co gamma-ray irradiation on commercial nuclear emulsions were studied at five different temperatures (+50°C, +20°C, 0°C, -10°C and -75°C). The exposed emulsions were developed by ID-19 type developer (1: 2) for 15 or 20 minutes at 20°C, and then fixed by sodium ammonium thiosulfate fixer. The fixing time was 30 minutes for 15μ thick emulsions and 90 minutes for 50 μ thick emulsions. Among the nuclear emulsions used, the cobalt-60 gamma-ray sensitivity of proton sensitive emulsions lay between several roentgens and several tens of roentgen, and that of the electron sensitive emulsions was several handreds of milliroentgen. The reduction of density by temperature change of irradiation was more pronounced on the proton sensitive emulsions than that of the electron sensitive ones. For most nuclear emulsions, the maxima of the sensitivity for the variation of temperature appeared at 20°C, but in some emulsions it appeared at 0°C or -10°C.