An ultrasonic diagnostic apparatus according to an embodiment includes an image obtaining unit, a contour position obtaining unit, a volume information calculating unit, and a controlling unit. The image obtaining unit obtains a plurality of groups of two-dimensional ultrasound image data each of which is generated by performing ultrasound scans, the ultrasound scans being performed on each of a plurality of predetermined cross-sectional planes, and performed for predetermined time. The contour position obtaining unit obtains, by performing a tracking process over the predetermined time period, time-series data of contour positions, the contour positions being either one of, or both of, a cavity interior and a cavity exterior of a predetermined site. The volume information calculating unit calculates, on a basis of a plurality of the time-series data of contour positions, volume information of the predetermined site. The controlling unit exercises control so as to output the volume information.
