An ultrasonic diagnostic apparatus by which highly quantitative IMT (intima media thickness) measurement with little variations depending on examiners can be performed. The ultrasonic diagnostic apparatus includes: an ultrasonic probe 100 for transmitting ultrasonic waves to an object to be inspected and receiving ultrasonic echoes generated by reflection of the ultrasonic waves in the object to output reception signals a signal processing unit 28 for performing at least envelope detection processing on the reception signals outputted from the ultrasonic probe to generate envelope data a boundary detecting unit 41 for detecting two boundaries representing intima media of a blood vessel based on difference or differential of values of the envelope data and amounts of change in the values of the envelope data and an IMT calculating unit 46 for calculating an IMT of the blood vessel based on the two boundaries detected by the boundary detecting unit.
