A backside-illuminated active pixel sensor array in which crosstalk between adjacent pixels is prevented, a method of manufacturing the backside-illuminated active pixel sensor array, and a backside-illuminated image sensor including the backside-illuminated active pixel sensor array are provided. The backside-illuminated active pixel sensor array includes a semiconductor substrate of a first conductive type that comprises a front surface and a rear surface, light-receiving devices for generating charges in response to light incident via the rear surface, and one or more pixel isolating layers for forming boundaries between pixels by being disposed between the adjacent light-receiving devices, a wiring layer disposed on the front surface of the semiconductor substrate, and a light filter layer disposed on the rear surface of the semiconductor substrate, wherein a thickness of the one or more pixel isolating layers decreases from a point in the semiconductor substrate toward the rear surface.