A lesion area detection unit detects an abnormal peripheral structure (lesion area), a pulmonary blood vessel extraction unit extracts a branch structure (pulmonary blood vessel) from the three-dimensional medical image, an associated blood vessel identification unit identifies an associated branch structure functionally associated with the abnormal peripheral structure based on position information of each point in the extracted branch structure, and an associated lung parenchymal area identification unit identifies an associated peripheral area (lung parenchyma) functionally associated with the identified associated branch structure based on the position information of each point in the extracted branch structure.