There is provided an automatic door sensor device (1) capable of preventing a door (3) which is transitioning from an open position to a closed position from being erroneously detected as an object by temporarily changing a detection area (A, C2, C3). The automatic door door sensor device (1) includes a doorway area door sensor (7a) that detects the presence of an object in a doorway area (B) which includes at least a portion of an area defined by the path of a door (3), detectors (6, 7b) that detects the presence and/or the movement of an an object in changeable detection areas (A, C2, C3), and a detection area changer (3 1) that changes the detection areas (A, C2, C3) when it is determined, by using the doorway area door sensor (7a), that the door (3) is transitioning from an open position to a closed position.