The inspection apparatus includes: a stage that retains the inspection sample; a light irradiator that irradiates the inspection sample with light having a predetermined wavelength to cause the inspection sample to emit a terahertz wave; a detector that detects electric field intensity of the terahertz wave emitted from the inspection sample; and a comparator that compares the electric field intensity of the terahertz wave emitted from the inspection sample to an evaluation reference value. The evaluation reference value is a value (for example, 90% of a saturation value) smaller than an absolute value of the saturation value of the electric field intensity of the terahertz wave, the terahertz wave being generated by irradiating a reference sample, which is a reference of the inspection sample, with the light while different voltages are applied to the reference sample.