PURPOSE: To obtain a high-sensitivity cell by constituting a cell body with materials whose acoustic impedance is approximaterly equal to acoustic impedances of a stored solution and a piezoelectric film and adding an electric signal taking- out lead wire to the piezoelectric film.

CONSTITUTION: A piezoelectric film 4 is attached to cover the outside circumference of glass or quartz glass of a cell body 1, and they are brought closely into contact with each other by an epoxy adhesive, a silicone grease, or the like for the purpose of preventing a considerable attenuation of pressure waves due to penetration of air between the outside circumferential face and the film 4. Both faces of the piezoelectric film 4 are electrodes, and lead wires 7 are added, and one is earthed, and the other is connected to an amplifier. A sample solution is introduced into a storage part 8 from a leading-in part 2 and is filled up there, and light from a light source is irradiated into the storage part 8 through a transmission member 3 in the direction of a arrow X, and acoustic waves are generated in the sample solution, and a pressure is sensed through the cell body 1 by the piezoelectric film 4 to generate p potential. This potential is measured through the amplifier.