A nondestructive carrier concentration measuring device (100) includes: a storage unit (101) that stores a correlation between the reflectance of an inorganic compound semiconductor against terahertz light and a carrier concentration; a light radiation unit (103) that irradiates the terahertz light (105) to the inorganic compound semiconductor as a sample; a detection unit (109) that detects reflected light (108) of the inorganic compound semiconductor against the irradiated terahertz light (105); a reflectance calculation unit (111) that compares the irradiated terahertz light (105) with the reflected light (108) and calculates an actual measurement value of the reflectance of the inorganic compound semiconductor; and a read unit (113) that refers to the stored correlation and reads the carrier concentration of the sample corresponding to the actual measurement value of the reflectance.