An ultrasound diagnostic apparatus includes a transmitter, a receiver and a hardware processor. The transmitter outputs a drive signal for a C-mode image to an ultrasound probe. The receiver obtains a reception signal from the probe. The processor sets at least one mask in a frame of packet data of the reception signal; calculates a covariance matrix from a plurality of packet data included in the mask; calculates an eigenvector for the mask from the covariance matrix; calculates a first filter coefficient for the packet data by using the eigenvector and a gain matrix; performs interpolation on the first filter coefficient to calculate a second filter coefficient for packet data of each position in the frame; filters the packet data of the position by using the second filter coefficient; and generates C-mode image data from the filtered packet data.