An evaluation system includes an acquisition module that acquires a safety program, an instruction extraction module that extracts an instruction directed to processing for causing a target device to operate with safety maintained, a signal extraction module that extracts an input signal and an output signal related to the instruction, a setting module that displays the extracted input signal and the extracted output signal in association with each other, and receives a setting of an expected output value for the displayed output signal, the expected output value being a value for causing the target device to operate with safety maintained, and an evaluation module that changes a value of the extracted input signal and determines whether a value of the output signal calculated by an operation in accordance with the safety program, in response to change of the value of the input signal, is identical to the expected output value.