1. A measuring system for measuring light generated from a luminescent or fluorescent substance included in a liquid to be measured, or radiation included in the liquid to be measured, comprising a separating device for separating the liquid to be measured, an image pickup device for picking up an image of the liquid separated by the separating device, and a boundary calculating device for determining boundaries of the separated liquid picked up by the image pickup device, wherein the measuring system measures the light or the radiation in areas of the liquid divided by the boundary calculating device, respectively; the separating device is a flat plate grooved in a predetermined size; an edge enhancing device is provided for enhancing, as edges, the shading differences in the image of the separated liquid in the flat plate picked up by the image pickup device; a flow path position extracting device is provided for extracting, based on design information on grooves having the predetermined size in the flat plate, and the flat plate, flow path positions of the grooves by adjusting pixel positions of the grooves in the image with the edges enhanced by the edge enhancing device; and the boundary calculating device determines the boundaries based on the image in the pixel positions adjusted by the flow path position extracting device.