To implement a test meeting the need of the digitalization of a nuclear power plant control system.

A control device 161 includes: an input part 161a as a test signal input part to which a test signal from a test device is input; an input part 161b as an execution instruction signal input part to which an execution instruction signal instructing a test execution is input; a simulation signal transmission part 161d as simulation signal transmission part which transmits a simulation signal; a signal changeover part 161e as a signal changeover part which transmits the test signal input in the test signal input part when the execution instruction signal is input to the execution instruction signal input part and which transmits the simulation signal transmitted from the simulation signal transmission part 161d when the execution instruction signal is not input to the execution instruction signal input part.