A molecular detection apparatus according to a embodiment includes: a collection unit which collects detection target gases each containing molecule to be detected; a concentration adjusting unit which dilutes and/or concentrates the molecule, and generates a plurality of detection target gases having different concentrations of the molecule; a detection unit to which the plurality of detection target gases are sequentially introduced, and which includes a plurality of detection cells each outputting detection signals based on the concentrations of the molecule in the plurality of detection target gases; and a discrimination unit which discriminates the molecule by change tendencies of the detection signals based on the concentrations of the molecule.