1. An ultrasonic diagnosis apparatus which performs a scan of an interior of a subject to obtain two-dimensional image data of the interior, creates and outputs a two-dimensional ultrasound image of the interior based on the two-dimensional image data, and detects a posit ion and an orientation of a scanning plane of the scan according to which the two-dimensional image data is obtained, the ultrasonic diagnosis apparatus comprising: an image processing controlling unit that creates a guide image which corresponds to an anatomical position and orientation of the two-dimensional ultrasound image based on anatomical image data, which is previously stored as anatomical image data of a human body, and the position and the orientation of the scanning plane; a display unit that outputs and displays various types of images including the guide image and the two-dimensional ultrasound image so that plural images are simultaneously output and displayed; and a sample point detecting unit that detects, from the subject, positions of sample points that correspond to feature points on the anatomical image data, wherein the image processing controlling unit sets a nonorthogonal feature point three-axis coordinate system on the anatomical image data based on the feature points, sets in a space where the subject is in a nonorthogonal sample point three-axis coordinate system that anatomically corresponds to the feature point three-axis coordinate system based on the sample points, converts the detected position and orientation of the scanning plane into a position and an orientation on the sample point three-axis coordinate system, converts the position and the orientation obtained as a result of conversion into a position and an orientation on the feature point three-axis coordinate system, and creates the guide image based on the position and the orientation on the feature point three-axis coordinate system obtained as a result of conversion.