1. An information processing apparatus comprising: an ROI acquisition unit configured to acquire a position of an ROI (Region Of Interest) in an object on a reference coordinate system; a position/orientation acquisition unit configured to acquire a position and an orientation of an ultrasonic tomographic image acquired by an ultrasonic probe; an estimation unit configured to estimate a corresponding position of the ROI on an ultrasonic coordinate system, whose axes are defined by the plane of the ultrasonic tomographic image, based on at least the position of the ROI acquired by said ROI acquisition unit and the position and the orientation of the ultrasonic tomographic image acquired by said position/orientation acquisition unit; an existence region calculation unit configured to calculate an existence region, which represents the corresponding position where the ROI may exist on the ultrasonic coordinate system, by expanding an area around the corresponding position estimated by said estimation unit; a cross region calculation unit configured to calculate a cross region between the existence region calculated by said existence region calculation unit and the ultrasonic tomographic image based on information of the existence region and information of the position and the orientation of the ultrasonic tomographic image acquired by said position/orientation acquisition unit; and a display control unit configured to display the ultrasonic tomographic image and a body mark indicating a portion to be examined, and to display the existence region calculated by said existence region calculation unit and the cross region calculated by said cross region calculation unit on the body mark.