An object detection apparatus (100, 200, 300, 400) comprising: a light emission unit including a light source to emit light to an object; a light receiving unit including a light detector (22a, 22c) to receive light reflected from the object; a signal processing unit including a signal detector to be input with an output signal of the light detector (22a, 22c) or a signal that is acquired by processing the output signal of the light detector (22a, 22c), the signal processing unit further including an averaging/accumulating processing unit; and a control unit to set at least one area in a light emission region of the light emission unit as a target area, and to set at least one of a light emission condition of the light emission unit and a processing condition of the signal processing unit such that the at least one of the light emission condition and the processing condition are different between a time when the light is emitted to the target area in the light emission region and a time when the light is emitted to a background area in the light emission region, wherein the background area is a target-not-specified area; characterized in that the control unit is configured to provide control to at least one of the light source and the averaging/accumulating processing unit such that the signal level of received light reflected from the object becomes greater than a first threshold when the object exists in the target area, and the signal level of received light reflected from the object becomes greater than a second threshold and smaller than the first threshold when the object exists in the background area, wherein the first threshold is set greater than the noise level and the second threshold is set greater than the noise level and smaller than the first threshold; wherein the control unit is configured to control s the light emission unit to continuously emit the light to the target area for a plurality of times, wherein the averaging/accumulating processing unit is configured to perform averaging and accumulating for a plurality of the output signals of the light detector (22a, 22c) obtained by continuously emitting the light to the target area for the plurality of times, and to output the obtained signals to the signal detector. a light emission unit including a light source to emit light to an object; a light receiving unit including a light detector (22a, 22c) to receive light reflected from the object; a signal processing unit including a signal detector to be input with an output signal of the light detector (22a, 22c) or a signal that is acquired by processing the output signal of the light detector (22a, 22c), the signal processing unit further including an averaging/accumulating processing unit; and a control unit to set at least one area in a light emission region of the light emission unit as a target area, and to set at least one of a light emission condition of the light emission unit and a processing condition of the signal processing unit such that the at least one of the light emission condition and the processing condition are different between a time when the light is emitted to the target area in the light emission region and a time when the light is emitted to a background area in the light emission region, wherein the background area is a target-not-specified area; characterized in that the control unit is configured to provide control to at least one of the light source and the averaging/accumulating processing unit such that the signal level of received light reflected from the object becomes greater than a first threshold when the object exists in the target area, and the signal level of received light reflected from the object becomes greater than a second threshold and smaller than the first threshold when the object exists in the background area, the signal level of received light reflected from the object becomes greater than a first threshold when the object exists in the target area, and the signal level of received light reflected from the object becomes greater than a second threshold and smaller than the first threshold when the object exists in the background area, wherein the first threshold is set greater than the noise level and the second threshold is set greater than the noise level and smaller than the first threshold; wherein the control unit is configured to control s the light emission unit to continuously emit the light to the target area for a plurality of times, wherein the averaging/accumulating processing unit is configured to perform averaging and accumulating for a plurality of the output signals of the light detector (22a, 22c) obtained by continuously emitting the light to the target area for the plurality of times, and to output the obtained signals to the signal detector.