In CNC machining, NC data created by CAM software is usually linearly interpolated. This linearly interpolated tool path, however, may degrade the dynamic motion performance of the machine tool and the geometric accuracy in comparison with the reference CAD data. Tool path smoothing can be an effective way to address these problems. In this paper, a five-axis tool path smoothing method is proposed based on dual cubic B-spline curves. The proposed smoothing method includes two steps. First, the tool orientation is adjusted to reduce drastic changes in tool orientation movement. Then, dual B-spline curves are generated for smooth interpolation of tool position and orientation, wherein their control points are created by using modified internal division points between the top and bottom points of the tool defined by given tool position and orientation vectors. The B-spline curves pass through the junctions of straight line segments comprising the top and bottom points, respectively. Smooth tool position and orientation vectors are finally obtained by simultaneous interpolation of the B-spline curves. The proposed method is implemented in a PC-based five-axis control system and experimentally demonstrated to show improvements in the dynamic motion performance and the geometric accuracy compared with the conventional linear interpolation.