We have established a novel structure elucidation system that predicts a structure of unknown compounds. The success of the system largely depends on a heuristic algorithm to predict a structure by using 2D-NMR spectral data. The system corresponds to the process of “Whether it has been made”. First, the system generates all possible structures that agree input data of molecular formula and 2D-NMR spectrum. The structures are called candidate structures. Next, the system predicts the spectrum of candidate structures and ranks them according to their similarity to the input spectrum.