An apparatus for detecting materials includes a database for storing detecting spectra of detecting materials, and a tera-hertz wave applying unit for applying tera-hertz waves having a plurality of different frequencies around a boundary between a light wave frequency and a radio wave frequency, to a predetermined position of an inspecting object. The apparatus includes an output wave receiving unit for receiving an output wave that is the tera-hertz wave having been applied to the inspecting object, and a determining unit for determining whether or not the output wave includes the detecting spectrum.