A pulse laser oscillator (11) outputs a first laser beam, a beam splitter splitting the first laser beam into split beams, optical paths (12, 13, 14, 15, 16) propagating light of split beams split, respectively, taking different times for light propagation thereof, a condenser superimposing light of split beams propagated through the optical paths, respectively, on an identical spot of a measuring material (100), for irradiation therewith, a laser interferometer (30) irradiating the measuring material (100) with light of a second laser beam, having light intensity variations resulted from interferences between reference light and light of the second laser beam reflected or scattered, as bases to detect ultrasonic waves energized by light of the first laser beam and transmitted in the measuring material (100), a waveform analyzer (32) calculating a metallic microstructure or a material property of the measuring material (100) based on ultrasonic waves.