To prevent the generation of any unexpected mechanical operation due to the unprepared change of any parameter, and to achieve the improvement of safety and the outflow prevention of an additional value.

This parameter setting device is provided with a parameter storage means 12 for input/output corresponding to a parameter storage means 11 for actual control; and a parameter conversion means 13 for performing the conversion processing of a parameter for input according to a setting rule R from a parameter storage means 12 for input/output to the parameter storage means 11 for actual control. The setting content of the parameter storage means 11 for actual control is not displayed to the outside, and the input of the parameter is performed through the parameter storage means 12 for input/output. The setting rule R is set by using a machine number or the like which is unique to each machine.