To provide a workpiece machining method for a workpiece machining machine capable of manufacturing a product having machining precision within a specification without interrupting machining work.

In this workpiece machining method for the workpiece machining machine for detecting a reference position of a workpiece W by bringing a contact 60 into contact with the workpiece W to machine the workpiece W based on the reference position, a position calculated based on data of a machining reference face position set by other workpiece W in the past is set as a machining reference face position of the workpiece if it is judged that a contact face 75 of the contact 60 is not in contact with a machining reference face M normally to perform machining based on the machining reference face position. Consequently, a position more approximate to a true reference position of the workpiece which can be detected if the contact face of the contact is in contact with the machining reference face normally is set as a machining reference face position to bring machining precision of the product into the specification with high probability and reduce the frequency of occurrence of a product out of specification markedly.