A pump probe measuring device (1) comprises: an ultrashort optical pulse laser generator (2) for generating a first ultrashort optical pulse train which is a pump light (3a), second and third ultrashort optical pulse trains (3b), (3c) which are probe lights; an optical shutter unit (6) to which the second and the third ultrashort pulse trains (3b), (3c) are introduced; and a detecting unit (20) including an irradiation optical system (8) for directing the pump light (3a), the first probe light (3b) and the second probe light (3c) to a sample (7), a sensor (11) for detecting a probe signal from the sample (7), and a phase-sensitive detecting means (12) connected to the sensor (11). An optical shutter control unit (10) periodically modulates the delay time of the first probe light (3b) and that of the second probe light (3c) with respect to the pump light (3a), and the modulated first and second probe lights (3a), (3b) illuminate the sample (7) alternately to detect the probe signals from the sample (7) by the phase-sensitive detecting means (12) in synchronization with the periodic modulation signal of the delay time.