A machined shape determining step of determining a machined shape machined by a basic tooling or basic tooling template of each machining efficiency group from a material shape (S19), a tooling determining step of determining an optimal tooling comprising a combination of a tool, a holder and a tool projection length on the basis of information of the tools and the holders, stored in a tool holder information storage unit, the combination having a maximum machining efficiency and being able to form the material shape into a corresponding one of the machined shapes without interfering with the machined shape (S20), a process candidate determining step of determining an optimal process candidate using the optimal tooling of each machining efficiency group (S21), and a process determining step of determining an optimal process on the basis of the optimal process candidate of each machining efficiency group (S10), are executed.