A monitoring system comprising a plurality of image capturing devices that capture images of a plurality of monitoring target devices, output devices that output operation information of the plurality of monitoring target devices, a display device that displays information, a control device that controls the display device, and a storage device that stores information; the storage device storing, in an associated manner, image capturing information obtained in image capturing of each of the plurality of image capturing devices, image capturing time information indicating the time when the image capturing information was captured, and identification information of the monitoring target devices for which the image capturing information was captured, and the storage device also storing, in an associated manner, the operation information output by each of the plurality of output devices, operation time information indicating the time when the operation information was obtained, and identification information of the monitoring target devices related to the operation information; and the control device, when an abnormality has occurred in an operation state of any of the plurality of monitoring target devices, executing a first display control that causes the display device to display abnormality occurrence information including at least identification information of the monitoring target device in which the abnormality has occurred and occurrence time information indicating the time when the abnormality occurred; and the control device, when one item, or one item among two or more items, of the abnormality occurrence information displayed in the display device has been selected, executing a second display control that acquires the image capturing information of the monitoring target device corresponding to the selected abnormality occurrence information from the storage device and causes the display device to display the acquired image capturing information, and executing a third display control that acquires the operation information of the monitoring target device corresponding to the selected abnormality occurrence information from the storage device and causes the display device to display the acquired operation information, the control device sets an image capturing display area and an operation information area in a display screen of the display device, executes the second display control using the image capturing display area, and executes the third display control using the operation information area, wherein the third display control is a control that displays information indicating a change in the operation state of the monitoring target device in the set time period including the time at which the abnormality according to the selected abnormality occurrence information occurred as the operation information. the storage device storing, in an associated manner, image capturing information obtained in image capturing of each of the plurality of image capturing devices, image capturing time information indicating the time when the image capturing information was captured, and identification information of the monitoring target devices for which the image capturing information was captured, and the storage device also storing, in an associated manner, the operation information output by each of the plurality of output devices, operation time information indicating the time when the operation information was obtained, and identification information of the monitoring target devices related to the operation information; and the control device, when an abnormality has occurred in an operation state of any of the plurality of monitoring target devices, executing a first display control that causes the display device to display abnormality occurrence information including at least identification information of the monitoring target device in which the abnormality has occurred and occurrence time information indicating the time when the abnormality occurred; and the control device, when one item, or one item among two or more items, of the abnormality occurrence information displayed in the display device has been selected, executing a second display control that acquires the image capturing information of the monitoring target device corresponding to the selected abnormality occurrence information from the storage device and causes the display device to display the acquired image capturing information, and executing a third display control that acquires the operation information of the monitoring target device corresponding to the selected abnormality occurrence information from the storage device and causes the display device to display the acquired operation information, the control device sets an image capturing display area and an operation information area in a display screen of the display device, executes the second display control using the image capturing display area, and executes the third display control using the operation information area, wherein the third display control is a control that displays information indicating a change in the operation state of the monitoring target device in the set time period including the time at which the abnormality according to the selected abnormality occurrence information occurred as the operation information.