Abstract: There is provided an initializing method for a programmable machine controller, whereby various control parameters of the programmable machine controller can be initialized quickly. The initial values of the various parameters, stored in a random access memory for initial-value setting of the controller, are transferred to a blank region of another random access memory for storage therein (S1.about.S4), and then transferred to a read-only memory (ROM) cassette for storage therein (S5). When a command for parameter initialization is delivered with the controller loaded with the ROM cassette, the various parameters are initialized using the initial values stored in the cassette.