MONITORING DEVICE

PROBLEM TO BE SOLVED: To provide a monitoring device capable of preventing the web break. SOLUTION: This monitoring device is obtained by arranging a light source 9 on the upper side of a wet web 1, directing the luminous surface thereof downward, installing a camera 5a on the operating side and a camera 5b on the driven side on the side opposite to the light source 9 with the wet web 1 placed therebetween, directing the lens surfaces thereof upward, reflecting the light from the light source 9 from a mirror 11, passing the reflected light through the wet web 1, catching the reflected light with the cameras 5a and 5b, thereby taking a silhouette (image) of the light from the light source 9 passing through the wet web 1 with the cameras 5a and 5b, sending the image to an image processing unit 6, carrying out image processing thereof, detecting coordinates of a border line where the wet web 1 separates from a center roll 2 from the image taken from the two directions, sending values of the coordinates to a computer 8, converting the values of the coordinates into a shift at each sampling period with the computer 8 and determining the quantity of fluctuation of a peeling point 3 and the whole shapes of peeling lines 3a and 3b. Thereby, an abnormality in a machine leading to web break can be predicted beforehand.