A measurement data processing system capable of recognizing a measurement value stably without being subject to the influence of an environment is configured including a measuring instrument having a display part to display a measurement result, the display part being provided with a light source; a plurality of measuring instrument identification media placed on the display part of the measuring instrument and having respectively different transmittances of light from the light source; an image acquisition means that captures an image of a measurement result displayed on the display part and of the measuring instrument identification media; and a measurement data processing device that determines what is identified by the measuring instrument identification media from the image acquired, recognizes a measurement result according to image processing parameters retrieved based on measuring instrument identification information determined, and outputs measurement data or error data.