This report deals with the scanning acoustic microscope for imaging cross sectional characteristic acoustic impedance of biological soft tissues. A focused pulse wave is transmitted to the object placed on the "rear surface" of a plastic substrate. The reflected signals from the target and reference are interpreted into local acoustic impedance. Two-dimensional profile is obtained by scanning the transducer. This method, using a spherical transducer, produces a significant aberration, because the sound speed of the substrate is different from water that is used as a coupling medium. For this reason the spatial resolution is reduced. The spatial resolution was improved by using 3D deconvolution technique, considering the impulse response of the acoustic system. In addition, as the incidence is not vertical, not only longitudinal wave but also transversal wave is generated in the substrate. Calibration for acoustic impedance was carried out after the deconvolution process, considering the above mentioned oblique incidence.