A leaf area index measurement system includes: a reflector placed in a neighborhood of a measurement target plant； imaging means placed at a position where no obstacle is present between the imaging means and the reflector, and for capturing an image of the reflector and outputting the captured image； intensity calculation means for calculating an intensity of light reflected by the reflector, based on the captured image output from the imaging means； and leaf area index calculation means for calculating a leaf area index, based on the intensity of light calculated by the intensity calculation means.
