In many procedures important in engineering and science, such as plastic working, tensile, bending, creep and fatigue tests, both the geometrical shape and material properties of objects change simultaneously. Therefore, simultaneous measurement of these quantities has been sought. In this paper we present a novel method for simultaneous imaging of the thickness of and sound velocity in a plate. After evaluating the accuracy of this method in a low-temperature acoustic microscope, it was applied to a stainless steel plate that underwent the stress-induced martensitic transformation, and thickness and sound velocity images around a notch in the plate were obtained. Since the thickness and velocity images differ slightly, the possibility of independent but simultaneous imaging of plate thickness and sound velocity was confirmed.