Abstract: Out-of-band response is a very important parameter of UVFPA detectors. As a wide-gap semiconductor material, AlGaN based ultraviolet detector exhibits excellent performance of the out-of-band response and rejection in ultraviolet detection. Visible blind AlGaN 6408 pixel ultraviolet focal plane arrays (UVFPA) detector was reported, whose spectral response range is 345-363.5 nm. To characterize the out-of-band response of the detector over a wide spectral range, by monochromatic spectral scanning, a response spectrum of the UVFPA was obtained with a wide range from UV to near IR. The result shows that the UVFPA detector has an excellent performance of out-of-band response. The ratio is 1.14% over the whole spectral band from 300 to 1 160 nm.