An apparatus for tracking an posture of a moving object in a three-dimensional space having a z-axis facing a reference surface of the moving object, an x-axis perpendicular to the z-axis in a virtual vertical plane including the z-axis, and a y-axis perpendicular to the x-axis in a virtual horizontal plane including the x-axis is described. A reference surface direction determination unit detects which direction the reference surface is facing with the x-axis as an axis of rotation. The x-axis deviation determination unit detects how far an x-axis direction of the moving object is relatively deviated from a magnetic north direction. The determination unit determines the posture of the moving object based on how far the x-axis of the moving object is deviated and which direction the reference surface is facing in response to detection signals of the reference surface direction determination unit and the x-axis deviation determination unit.