A plasma observation system includes a plasma processing apparatus which includes a processing container in which a substrate is processed with plasma, and a plurality of observation windows each capable of observing an emission state of the plasma in the processing container; and a measuring device including a light receiver configured to receive a plurality of light beams intersecting in the processing container through a plurality of observation windows, and a controller configured to specify an observation point of the plasma and determine a state of the plasma at the observation point based on the plurality of light beams received by the light receiver.