A structure for adjusting the positional relationship between an ultrasonic transducer and a blood vessel such that an acoustic line from the ultrasonic transducer passes the center of a cross-section of the blood vessel for measuring an elasticity characteristic is provided.An ultrasonic probe includes a transducer for transmitting an ultrasonic wave and receiving the ultrasonic wave reflected by a tissue of a biological body; and a driving device for physically moving the transducer. For measuring the elasticity characteristic of the blood vessel by an ultrasonic diagnostic apparatus, the driving device moves the transducer based on a control signal from the ultrasonic diagnostic apparatus to change at least one of a direction and a position at which the ultrasonic wave is to be transmitted. A determination section of the ultrasonic diagnostic apparatus specifies a position of the transducer at which the reflection intensity is maximum based on intensity information representing an intensity of the reflected wave. A calculation section of the ultrasonic diagnostic apparatus calculates the elasticity characteristic of the blood vessel at the specified position.