A human body detection sensor having a high detection performance and an automatic faucet having high operational reliability are provided. The human body sensor 1 includes a distance measurement determiner 321 which determines the existence of the detection target depending on whether or not the distance index representing a distance to the detection target or a degree of the distance is included in a predetermined range, and a moving object determiner 322 which detects a temporal change of the reflected light entering the light reception portion 26 and determines whether or not the moving object exists. While when the light reception amount of the reflected light under the detection state is the predetermined threshold or more, the detection determiner 321 switches the determination from the detection state to the non-detection state under a condition that the distance measurement determiner determines that the detection target does not exist, when the light reception amount of the reflected light under the detection state is less than the predetermined threshold, the detection determiner switches the determination from the detection state to the non-detection state under a condition that the moving object determiner 322 determines that the moving object does not exist.