PROBLEM TO BE SOLVED: To provide a control rod drive controlling system that has the advantage of both a daisy chain type and a duplexing star type.SOLUTION: A control rod drive controlling system according to an embodiment has: a control device; an electromagnetic valve; a control rod drive device; and cable units. The control rod drive device generates an excitation signal for driving the electromagnetic valve by receiving a signal from the control device. The cable units are provided between the control rod drive device and the electromagnetic valve in association with each of control rods. Each cable unit has first wire that transmits the excitation signal for the electromagnetic valve to be connected to an own cable unit out of the excitation signals input directly from the control rod drive device or via the cable units at a front stage. Each of the cable units other than those at a rear stage has second wire for outputting other excitation signal to the cable units at the rear stage.
