To provide a lighting control system capable of favorably maintaining the detection accuracy of a human body while reducing a process load related to image processing.

A thinning means performs thinning processing by applying one of a plurality of thinning patterns, to an image Im, different in the distribution of effective pixels P1 within a sight field of a camera which remain after the thinning processing. During a period while a lighting fixture is turned off, a thinning pattern with the effective pixels P1 concentrated in the outer peripheral portion is applied because the outer peripheral portion of the sight field of the camera is heavily monitored to detect the intrusion of a human body into the sight field of the camera. On the other hand, during a period while the lighting fixture is turned on, a thinning pattern with the effective pixels P1 distributed across the entire sight field of the camera is applied to monitor the entire sight field of the camera for detecting the presence of the human body in the sight field of the camera.