PROBLEM TO BE SOLVED: To provide a breath analysis system which can identify the possibility of lung cancer with great accuracy using breath.SOLUTION: A breath analysis system includes a determination unit for determining whether it is possible that a subject has lung cancer or not on the basis of breath components selected from at least one group of components selected from a first group comprising Butane and Methylcyclohexane a second group comprising two or more components selected from Acetone, CHO, and CHO a third group comprising Acetic acid and Furan a fourth group comprising Acetic acid and Propanoic acid and a fifth group comprising two or more components selected from Propanoic acid, Acetoin, 1-Methylstyrene, and Nonanal.