A coating quality measuring device and a pattern plate including one reference pattern portion having a large pattern width and a plurality of strip pattern portions each having a smaller pattern width. The pattern plate is disposed opposite the coated surface. The pattern plate is reflected off the coated surface and a reflected image is formed on an image sensor. The image sensor successively outputs signals each corresponding to the light level of each strip pattern portion on a line extending in a width direction of each strip pattern portion of the reflected image. A computing device calculates an average signal level of the signals outputted by the image sensor, divides the difference between the average signal level and the signal level of each signal by the signal level of the reference pattern portion and calculates a square average value of the obtained division value to obtain a measure of the coating quality of the coated surface.
