1. An ultrasonic diagnostic apparatus comprising: an ultrasonic probe 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; signal processing means for performing at least envelope detection processing on the reception signals outputted from said ultrasonic probe to generate envelope data; image data generating means for generating image data representing an ultrasonic image on the object based on the envelope data; pre-measurement processing means for performing structural image generating processing on the envelope data; and measuring means for performing measurement based on the envelope data processed by said pre-measurement processing means.