A measuring device includes: an irradiator that irradiates electromagnetic waves to an inspection object; a light collector having a reflecting surface that guides, to a light-collecting surface, electromagnetic waves whose incident angle with respect to an incident end facing the inspection object is within a predetermined angle, among the electromagnetic waves that have been transmitted through the inspection object; and a detector that detects the electromagnetic waves guided to the light-collecting surface. The measuring device measures a characteristic of the inspection object based on the detected electromagnetic waves.