An ultrasonographic device includes an ultrasonic wave transmitter/receiver section which transmits and receives ultrasonic waves to and from a test subject through a probe, a phasing addition circuit which controls the phase of the received ultrasonic wave and generates RF signal frame data, an RF signal frame data selection section which makes variable the frame interval of the RF signal frame data to be outputted, and an elastic image generating section which sets the optimum imaging range for each elastic frame data generated based on the RF signal frame data and generates elastic image.