An object of the present subject matter is to appropriately acquire and analyze a camera image for monitoring and to constantly monitor a monitoring target with high accuracy. A programmable logic controller (PLC) includes: an image processing section for sequentially acquiring the image data of the camera image from the camera sensor and generating characteristic amount data indicating a characteristic amount of image data in a preset monitoring region; a time-series data acquisition section for sequentially collecting characteristic amount data from the image processing section and acquiring time-series data of a characteristic amount; and a monitoring section for monitoring time-series data of a current characteristic amount acquired by the time-series data acquisition section in accordance with a monitoring timing defined by the device of the device memory.