A subject information acquisition apparatus includes a converter configured to receive reflected waves from a contrast medium within a target area inside a subject, and a pressure information acquisition unit configured to acquire pressure information within the target area. In this case, the converter receives reflected waves from a contrast medium in each of a first period and a second period in which a pressure within the target area is different from the first period. The pressure information acquisition unit acquires pressure information in the second period within the target area based on a receive signal based on reflected waves in the first period, a receive signal based on a reflected wave in the second period, and pressure information on a region different from the target area, the pressure information being acquired in the first period.
