PURPOSE: To obtain an ultrasonic image which compensates an influence of the fluctuation of a medium, by making an object wave and a reference wave pass through a fluctuation medium at the same time, at the time of imaging an object being in a medium having the fluctuation, by an ultrasonic holography technique.

CONSTITUTION: A sound source 2 is brought close to an object 3 by a sound source position control part 13, and a two-dimensional distribution of an acoustic pressure generated by a mutual interference of an object wave 5 and a reference wave 6 which have been propagated in an underwater fluctuation 4 is received by a hologram surface constituted of a matrix- shaped pressure sensitive element 11 and an electrode 12. A voltage distribution corresponding to an acoustic pressure distribution on the hologram surface is displayed on a two-dimensional display 16 in a marine vessel 15 through a cable 14. The display 16 performs a reduction corresponding to a ratio of an ultrasonic wavelength and a reproducing optical wavelength, and thereafter, reproduces it. In this case, a reproducing light source 17 is varied as to its position in accordance with a position of a reference sound source 2', and a reproduced image 3' can be obtained correctly. In this way, an influence of a distortion can be compensat ed even in the sea having the cause of a propagation distortion, such as a tide, an ocean current, a temperature distribution, a density distribution or a salt concentration distribution, etc.