An image sensor configured to function, according to setting information, as a synchronous master that controls synchronous imaging performed by a plurality of different image sensors each functioning as a synchronous slave, or to function as a synchronous slave, the image sensor comprises: an imaging unit configured to perform imaging and output an image via a data bus; and a control unit, wherein, when the sensor is set to function as the synchronous master, the control unit is configured to control imaging performed by the imaging unit, and imaging performed by each of the different image sensors, wherein the control unit uses: a generation circuit configured to generate a synchronous signal (Vsync) for controlling the imaging unit; a retention circuit configured to retain an acquisition state of a stop request; and a mask circuit configured to selectively output, in accordance with the stop request acquisition state of the retention circuit, the synchronous signal (Vsync) generated by the generation circuit as a synchronous slave synchronous signal (Vsync_out) to the different image sensors functioning as synchronous slaves that perform imaging under control by the synchronous master, and wherein, in a case where a stop request is acquired, the control unit is configured, by using the retention circuit and the mask circuit, to stop output to the different image sensors of the synchronous slave synchronous signal. an imaging unit configured to perform imaging and output an image via a data bus; and a control unit, wherein, when the sensor is set to function as the synchronous master, the control unit is configured to control imaging performed by the imaging unit, and imaging performed by each of the different image sensors, wherein the control unit uses: a generation circuit configured to generate a synchronous signal (Vsync) for controlling the imaging unit; a retention circuit configured to retain an acquisition state of a stop request; and a mask circuit configured to selectively output, in accordance with the stop request acquisition state of the retention circuit, the synchronous signal (Vsync) generated by the generation circuit as a synchronous slave synchronous signal (Vsync_out) to the different image sensors functioning as synchronous slaves that perform imaging under control by the synchronous master, and wherein, in a case where a stop request is acquired, the control unit is configured, by using the retention circuit and the mask circuit, to stop output to the different image sensors of the synchronous slave synchronous signal. a generation circuit configured to generate a synchronous signal (Vsync) for controlling the imaging unit; a retention circuit configured to retain an acquisition state of a stop request; and a mask circuit configured to selectively output, in accordance with the stop request acquisition state of the retention circuit, the synchronous signal (Vsync) generated by the generation circuit as a synchronous slave synchronous signal (Vsync_out) to the different image sensors functioning as synchronous slaves that perform imaging under control by the synchronous master, and wherein, in a case where a stop request is acquired, the control unit is configured, by using the retention circuit and the mask circuit, to stop output to the different image sensors of the synchronous slave synchronous signal.