An ultrasonic diagnostic apparatus according to an embodiment includes an acquiring unit and a detecting unit. The acquiring unit acquires fluid volume data representing fluid information related to a fluid flowing through a scan region that is a region three-dimensionally scanned by ultrasonic. The detecting unit detects a region that is a fluid existing region in the scanned region using the fluid information, and detects an inner cavity region of a lumen in volume data to be applied with image processing using the region thus detected.
