Inspection apparatus, inspection method, computer program and recording medium

An inspecting device is provided with: a radiating unit which radiates terahertz waves onto a sample laminated into a plurality of layers; a detecting unit which acquires a detected waveform by detecting terahertz waves from the sample; a selecting unit which selects a portion of a library representing an estimated waveform, on the basis of the detected waveform; and an estimating unit which estimates a position of an interface between the plurality of layers, on the basis of the detected waveform and the selected partial library.