An ultrasonic diagnostic apparatus including: an ultrasonic probe for transmitting and receiving ultrasonic waves while in contact with a test body, a transmitting unit for transmitting the ultrasonic waves to the ultrasonic probe, a receiving unit for receiving and processing an RF signal which is a reflected echo signal received by the ultrasonic probe, an image creating unit for creating an ultrasonic image based on the RF signal output from the receiving unit, a display unit for displaying the ultrasonic image created by the image creating unit, a control unit for controlling the transmitting unit and the receiving unit, and a pressurizing-state evaluation unit for evaluating the pressure applied to the test body based on the deformation of an elastic coupler which has been attached to an ultrasonic wave transmitter/receiver surface of the ultrasonic probe, wherein the pressurizing-state evaluation unit includes an initialization process unit for detecting the position of an exposure surface of the elastic coupler in an initial state in which the elastic coupler is not pressurized, and for obtaining the initial thickness of the elastic coupler, and a coupler pressurization evaluation unit for obtaining the thickness of the elastic coupler by detecting the boundary between the elastic coupler and the test body, obtaining the thickness change based on the thus obtained thickness and the initial thickness, and evaluating the pressure based on the thickness change and an elasticity property of the elastic coupler, characterised in that the initialization process unit is configured to detect the exposure surface of the elastic coupler based on a time from a point in time at which an ultrasonic signal is output from the transmitting unit to the ultrasonic probe to a point in time at which the intensity of the RF signal corresponding to the ultrasonic signal or the illuminance of the ultrasonic image exceeds a pre-set threshold value for the first time in the state where the elastic coupler is attached. an ultrasonic probe for transmitting and receiving ultrasonic waves while in contact with a test body, a transmitting unit for transmitting the ultrasonic waves to the ultrasonic probe, a receiving unit for receiving and processing an RF signal which is a reflected echo signal received by the ultrasonic probe, an image creating unit for creating an ultrasonic image based on the RF signal output from the receiving unit, a display unit for displaying the ultrasonic image created by the image creating unit, a control unit for controlling the transmitting unit and the receiving unit, and a pressurizing-state evaluation unit for evaluating the pressure applied to the test body based on the deformation of an elastic coupler which has been attached to an ultrasonic wave transmitter/receiver surface of the ultrasonic probe, wherein the pressurizing-state evaluation unit includes an initialization process unit for detecting the position of an exposure surface of the elastic coupler in an initial state in which the elastic coupler is not pressurized, and for obtaining the initial thickness of the elastic coupler, and a coupler pressurization evaluation unit for obtaining the thickness of the elastic coupler by detecting the boundary between the elastic coupler and the test body, obtaining the thickness change based on the thus obtained thickness and the initial thickness, and evaluating the pressure based on the thickness change and an elasticity property of the elastic coupler, characterised in that the initialization process unit is configured to detect the exposure surface of the elastic coupler based on a time from a point in time at which an ultrasonic signal is output from the transmitting unit to the ultrasonic probe to a point in time at which the intensity of the RF signal corresponding to the ultrasonic signal or the illuminance of the ultrasonic image exceeds a pre-set threshold value for the first time in the state where the elastic coupler is attached.