An ultrasound diagnostic apparatus (1, 1A, 1B) that has an ultrasound probe and is used to compression-test an observation target in a subject by pressing the ultrasound probe against a body surface of the subject, the ultrasound diagnostic apparatus (1, 1A, 1B)comprising: an image acquisition unit that performs transmission of an ultrasound beam from the ultrasound probe toward the subject to acquire ultrasound images (U1, U2, U3, U4) sequentially and consecutively; a display unit that displays the ultrasound image (U1, U2, U3, U4) acquired by the image acquisition unit; a reference image holding unit that holds the ultrasound image (U1, U2, U3, U4) acquired by the image acquisition unit in a state where a position of the ultrasound probe is fixed in order to depict a tomographic plane (FP1, FP2) of the observation target on the display unit as a reference image (C1, C3); a movement vector calculation unit that calculates a movement vector indicating an image movement change between two ultrasound images (U1, U2, U3, U4) that are consecutive for each predetermined number of frames among the ultrasound images (U1, U2, U3, U4) sequentially acquired by the image acquisition unit; a movement vector integration unit that integrates the movement vectors that are respectively calculated by the movement vector calculation unit in the ultrasound images (U1, U2, U3, U4) from a time when the reference image (C1, C3) is held by the reference image holding unit to a current time; a deformed image generation unit that generates a deformed image (D1, D3) in which the ultrasound image of a current frame acquired by the image acquisition unit is moved and changed tracing back to a time when the reference image (C1, C3) is held by the reference image holding unit based on a movement change integrated by the movement vector integration unit; a tomographic plane determination unit that determines whether a tomographic plane (FP1, FP2) of the subject depicted from the ultrasound image of the current frame and a tomographic plane (FP1, FP2) of the subject depicted from the reference image (C1, C3) are the same as each other by comparing the deformed image (D1, D3) generated by the deformed image generation unit with the reference image (C1, C3) held by the reference image holding unit; and a determination result notification unit that notifies a user of a determination result obtained by the tomographic plane determination unit. an image acquisition unit that performs transmission of an ultrasound beam from the ultrasound probe toward the subject to acquire ultrasound images (U1, U2, U3, U4) sequentially and consecutively; a display unit that displays the ultrasound image (U1, U2, U3, U4) acquired by the image acquisition unit; a reference image holding unit that holds the ultrasound image (U1, U2, U3, U4) acquired by the image acquisition unit in a state where a position of the ultrasound probe is fixed in order to depict a tomographic plane (FP1, FP2) of the observation target on the display unit as a reference image (C1, C3); a movement vector calculation unit that calculates a movement vector indicating an image movement change between two ultrasound images (U1, U2, U3, U4) that are consecutive for each predetermined number of frames among the ultrasound images (U1, U2, U3, U4) sequentially acquired by the image acquisition unit; a movement vector integration unit that integrates the movement vectors that are respectively calculated by the movement vector calculation unit in the ultrasound images (U1, U2, U3, U4) from a time when the reference image (C1, C3) is held by the reference image holding unit to a current time; a deformed image generation unit that generates a deformed image (D1, D3) in which the ultrasound image of a current frame acquired by the image acquisition unit is moved and changed tracing back to a time when the reference image (C1, C3) is held by the reference image holding unit based on a movement change integrated by the movement vector integration unit; a tomographic plane determination unit that determines whether a tomographic plane (FP1, FP2) of the subject depicted from the ultrasound image of the current frame and a tomographic plane (FP1, FP2) of the subject depicted from the reference image (C1, C3) are the same as each other by comparing the deformed image (D1, D3) generated by the deformed image generation unit with the reference image (C1, C3) held by the reference image holding unit; and a determination result notification unit that notifies a user of a determination result obtained by the tomographic plane determination unit.