Disclosed herein are a diagnostic method using laser induced breakdown spectrum analysis and a diagnostic device for performing the same. The diagnostic device may include a laser projection module projecting a pulsed laser to a specimen, a light receiving module receiving a light generated by a plasma ablation induced at the specimen by the pulsed laser, a spectral member receiving and dividing the light generated by the plasma ablation; a sensor array including a plurality of sensors arranged to receive the divided light for each wavelength, and a controller obtaining spectrum data of the light generated by the plasma ablation from a specific exposure period, and determining whether or not the specimen is diseased based on the spectrum data of the light generated by the plasma ablation.