Effect of γ-ray irradiations on the performance of InGaAs infrared detectors was studied. Planar-type 24×1 linear detector arrays were fabricated on n-InP/n-In<sub>0.53</sub>Ga<sub>0.47</sub>As/n-InP epitaxial structure by sealed-ampoule diffusion method. The InGaAs detectors were irradiated by 100krad, 300krad γ-ray at 40rad/s. The dark currents increased about 170%, 300% respectively and both decreased about 23% at the 8th hours and about 40% at the 22th hour after irradiation. Then the dark currents almost remained stable until 10 days after irradiation. Current-Voltage characteristics of the planar-type detector were analyzed. The current mechanisms were dominated by diffusion current, shunts current and generation-recombination current before irradiation. The γ irradiation resulted to increase these three current components. Ten days after irradiation, three current components all recovered partially. Capacitance-Voltage characteristics were measured before and after irradiation. Effective doping densities (N<sub>eff</sub>) of InGaAs layer were deduced by fitting 1/C<sup>2</sup>-V curves. N<sub>eff</sub> of detectors which were irradiated by 100krad γ-ray increased after irradiation and remained the same until 10 days after irradiation. N<sub>eff</sub> of detectors which were irradiated by 300krad γ-ray unchanged after irradiation. The response spectrums both moved slightly towards shorter wavelength after irradiation and stayed the same until at least 10 days after irradiation.