An ultrasound diagnostic apparatus comprising: a transducer array; a transmission unit that transmits a set of a first ultrasonic pulse and a second ultrasonic pulse having phases inverted from each other on the same scanning line from the transducer array into a subject N times equal to or greater than at least two times; a reception unit that acquires reception signals based on a signal output from the transducer array received an ultrasound echo generated in the subject; a quadrature detection unit that acquires an IQ signal string corresponding to the first ultrasonic pulse and an IQ signal string corresponding to the second ultrasonic pulse by performing quadrature detection in a determined range on the reception signals acquired by the reception unit; a tissue velocity detection unit that detects a velocity of a tissue in the subject based on the IQ signal strings acquired by the quadrature detection unit; a phase correction unit that corrects phases of the IQ signal strings acquired from each reflection position in the subject based on the velocity of the tissue detected by the tissue velocity detection unit such that an influence of the velocity of the tissue is cancelled; a pulse inversion addition unit that acquires added signals with a fundamental component eliminated by adding IQ signals corresponding to the first ultrasonic pulse and IQ signals corresponding to the second ultrasonic pulse adjacent in time series using the IQ signal strings with the phases corrected by the phase correction unit; and an image generation unit that generates an ultrasound image characterised in that: the determined range includes a frequency at which a nonlinear signal due to bubbles of a contrast agent introduced to the subject becomes maximum, a part of the frequency range of the fundamental component, and a part of the frequency range of a secondary harmonic component; the apparatus further comprises a nonlinear signal information calculation unit that calculates at least one of power or a velocity of the nonlinear signal from the added signals acquired by the pulse inversion addition unit; and the image generation unit generates the ultrasound image based on at least one of the power or the velocity of the nonlinear signal calculated by the nonlinear signal information calculation unit. a transducer array; a transmission unit that transmits a set of a first ultrasonic pulse and a second ultrasonic pulse having phases inverted from each other on the same scanning line from the transducer array into a subject N times equal to or greater than at least two times; a reception unit that acquires reception signals based on a signal output from the transducer array received an ultrasound echo generated in the subject; a quadrature detection unit that acquires an IQ signal string corresponding to the first ultrasonic pulse and an IQ signal string corresponding to the second ultrasonic pulse by performing quadrature detection in a determined range on the reception signals acquired by the reception unit; a tissue velocity detection unit that detects a velocity of a tissue in the subject based on the IQ signal strings acquired by the quadrature detection unit; a phase correction unit that corrects phases of the IQ signal strings acquired from each reflection position in the subject based on the velocity of the tissue detected by the tissue velocity detection unit such that an influence of the velocity of the tissue is cancelled; a pulse inversion addition unit that acquires added signals with a fundamental component eliminated by adding IQ signals corresponding to the first ultrasonic pulse and IQ signals corresponding to the second ultrasonic pulse adjacent in time series using the IQ signal strings with the phases corrected by the phase correction unit; and an image generation unit that generates an ultrasound image characterised in that: the determined range includes a frequency at which a nonlinear signal due to bubbles of a contrast agent introduced to the subject becomes maximum, a part of the frequency range of the fundamental component, and a part of the frequency range of a secondary harmonic component; the apparatus further comprises a nonlinear signal information calculation unit that calculates at least one of power or a velocity of the nonlinear signal from the added signals acquired by the pulse inversion addition unit; and the image generation unit generates the ultrasound image based on at least one of the power or the velocity of the nonlinear signal calculated by the nonlinear signal information calculation unit. the determined range includes a frequency at which a nonlinear signal due to bubbles of a contrast agent introduced to the subject becomes maximum, a part of the frequency range of the fundamental component, and a part of the frequency range of a secondary harmonic component; the apparatus further comprises a nonlinear signal information calculation unit that calculates at least one of power or a velocity of the nonlinear signal from the added signals acquired by the pulse inversion addition unit; and the image generation unit generates the ultrasound image based on at least one of the power or the velocity of the nonlinear signal calculated by the nonlinear signal information calculation unit.