PROBLEM TO BE SOLVED: To provide a subject information acquisition device which detects change in a subject position during measurement processing and can appropriately change the scanning path.SOLUTION: A subject information acquisition device acquires information on the inside of a subject by receiving and analyzing an acoustic wave from the inside of subject. The device comprises: scanning means 18 which scans the subject by using a probe for receiving the acoustic wave and path setting means 23 which determines a first path for the probe to perform scanning and position information acquisition means 22 which acquires position information about a position of the subject. The path setting means 23 determines whether to change the scanning path to a second path different from the first path on the basis of the position information.
