AlGaN/GaN heterostructure metal-semiconductor-metal (MSM) structure ultraviolet (UV) photodetector with Ni/Au electrodes is fabricated. Opto-electrical characteristics and current-voltage characteristics of the detector are investigated. It is found that the detector has two spectral response ranges. The peak response is 0.717 A/W at 288 nm and 0.641 A/W at 366 nm. The quantum efficiency is 308% at 288 nm and 217% at 366 nm.