[Object] The invention is intended to provide a medical image processing apparatus in which improvement of accuracy of boundary detection of a heart is achieved.[Solving Means] A medical image processing apparatus acquires volume data of a heat, detects a three-dimensional left ventricle coordinate system composed of three axes including at least a left ventricle long axis of the heart from the volume data uses a boundary model expressed in the left ventricle coordinate system and detects a left ventricle boundary from the volume data, and displays a cross-sectional image orthogonal to at least one axis of the three axes of the left ventricle coordinate system together with the detected left ventricle boundary on the cross-sectional image.