Currently used CAM systems for 5-axis machining can determine tool paths with collision-free tool postures. However, the algorithm implemented in the CAM systems sometimes generates un-optimum tool paths and postures from the viewpoint of machining processes and machine tool operation. This study proposes two methods to determine tool paths and tool postures for 5-axis machining based on the viewpoints of "human intuition" and "minimum cusp height" for resolving the problems. A method is developed for inputting the positions and postures of a cutting tool when executing virtual machining. In the execution of virtual machining, a virtual cutting tool can be intuitively moved by a haptic device to determine the desired locations and postures of the cutting tool. By using the system, the tool locations and tool postures to machine complicated shapes with overhang can be easily determined based on the operator's intuition. Another method is for determining tool postures for making minimum cusp height by matching the cutting edge of a flat end-mill to the cross-section shape at a point on surfaces to be machined. A basic system to determine the tool postures based on making minimum cusp height was developed. The cusp height on the surfaces generated by the basic system was smaller than the height generated by 3-axis ball-end milling.