An illumination control system for controlling illumination of lighting apparatuses (3A to 31), comprising: a communications line; and a plurality of the lighting apparatuses (3A to 31), each connected to the communications line, for illuminating light, wherein the plurality of the lighting apparatuses (3A to 31) are divided into a human detection control group for performing illumination control based on detection of a human being and a brightness detection control group for performing illumination control based on detection of ambient brightness such that two or more of the lighting apparatuses (3A to 31) belong to each group (50, 51), wherein each lighting apparatus (3A to 31) includes: a lamp; an illumination circuit configured to perform illumination control of the lamp; a communication unit configured to send or receive a control signal to and from another lighting apparatus (3A to 31) through the communications line; a control unit configured to control the illumination circuit based on the control signal to perform the illumination control of the lamp; and a sensor attaching part, wherein a lighting apparatus (3A, 3B or 3C) of the human detection control group includes a human detecting sensor attached to the sensor attaching part of said lighting apparatus (3A, 3B or 3C), the communication unit of said lighting apparatus (3A, 3B or 3C) sends a control signal including an operation instruction or an operation parameter representing information on presence of the human being in response to the detection of the human being by the human detecting sensor to each remaining lighting apparatus (3A, 3B or 3C) in the human detection control group, and, in each lighting apparatus (3A, 3B and 3C) of the human detection control group, the control unit controls the illumination circuit in accordance with the information on presence of the human being, and wherein a lighting apparatus (3A, 3D or 3E) of the brightness detection control group includes a brightness detecting sensor attached to the sensor attaching part of said lighting apparatus (3A, 3D or 3E), the communication unit of said lighting apparatus (3A, 3D or 3E) sends a control signal including an operation instruction or an operation parameter representing information on the ambient brightness in response to the detection of the ambient brightness by the brightness detecting sensor to each remaining lighting apparatus (3A, 3D or 3E) in the brightness detection control group, and, in each lighting apparatus (3A, 3D and 3E) of the brightness detection control group, the control unit controls the illumination circuit in accordance with the information on the ambient brightness. a communications line; and a plurality of the lighting apparatuses (3A to 31), each connected to the communications line, for illuminating light, wherein the plurality of the lighting apparatuses (3A to 31) are divided into a human detection control group for performing illumination control based on detection of a human being and a brightness detection control group for performing illumination control based on detection of ambient brightness such that two or more of the lighting apparatuses (3A to 31) belong to each group (50, 51), wherein each lighting apparatus (3A to 31) includes: a lamp; an illumination circuit configured to perform illumination control of the lamp; a communication unit configured to send or receive a control signal to and from another lighting apparatus (3A to 31) through the communications line; a control unit configured to control the illumination circuit based on the control signal to perform the illumination control of the lamp; and a sensor attaching part, a lamp; an illumination circuit configured to perform illumination control of the lamp; a communication unit configured to send or receive a control signal to and from another lighting apparatus (3A to 31) through the communications line; a control unit configured to control the illumination circuit based on the control signal to perform the illumination control of the lamp; and a sensor attaching part, wherein a lighting apparatus (3A, 3B or 3C) of the human detection control group includes a human detecting sensor attached to the sensor attaching part of said lighting apparatus (3A, 3B or 3C), the communication unit of said lighting apparatus (3A, 3B or 3C) sends a control signal including an operation instruction or an operation parameter representing information on presence of the human being in response to the detection of the human being by the human detecting sensor to each remaining lighting apparatus (3A, 3B or 3C) in the human detection control group, and, in each lighting apparatus (3A, 3B and 3C) of the human detection control group, the control unit controls the illumination circuit in accordance with the information on presence of the human being, and wherein a lighting apparatus (3A, 3D or 3E) of the brightness detection control group includes a brightness detecting sensor attached to the sensor attaching part of said lighting apparatus (3A, 3D or 3E), the communication unit of said lighting apparatus (3A, 3D or 3E) sends a control signal including an operation instruction or an operation parameter representing information on the ambient brightness in response to the detection of the ambient brightness by the brightness detecting sensor to each remaining lighting apparatus (3A, 3D or 3E) in the brightness detection control group, and, in each lighting apparatus (3A, 3D and 3E) of the brightness detection control group, the control unit controls the illumination circuit in accordance with the information on the ambient brightness.