An embedded controller development tool which generates an interface means for preserving and outputting a control data calculated by the control operation means based on a specific computational procedure, and providing said control data to a plurality of control operation means including said control operation means; wherein the control operation means is described as a function in the source code of the program, the reference data used for calculation by said control operation is an argument of the function, said control data calculated by said control operation means is the argument of the function which points the return value or the address of said function.