An acoustic microscope wherein an ultrasonic beam is projected on a sample through a propagating medium by an ultrasonic transducer having a short focus, reflected acoustic waves from the sample are detected by the transducer, and a microscopic image of the sample is obtained by scanning the sample mechanically in two dimensions, comprises a cover member which is interposed between the sample and the propagating medium and which has an acoustic impedance higher than those of the two. The intensity of a reflection signal depends upon multipath reflection within the cover member, and an intense reflection signal is obtained even for a sample which differs slightly in the acoustic impedance from the propagating medium.