1. An ultrasound diagnosis apparatus configured to generate virtual endoscopy image data based on volume data acquired through 3D scans over a diagnosing target region in an object, the ultrasound diagnosis apparatus comprising: a viewing point/direction setting unit configured to set a viewing point and a viewing direction to the volume data; a virtual endoscopy image data generating unit configured to generate virtual endoscopy image data by processing the volume data based on the viewing point and the viewing direction; a reference point setting unit configured to set a reference point on the diagnosing target region of the volume data based on the virtual endoscopy image data; a multi-planar-reconstruction (MPR) plane setting unit configured to set at least one MPR cross-sectional plane to the volume data based on the reference point; a MPR image data generating unit configured to generate MPR image data based on the volume data on the MPR cross-sectional plane; and a display unit configured to display both the virtual endoscopy image data and the MPR image data.