An evaluation system for evaluating functional safety of a safety program for causing a target device to operate so as to ensure safety of workers, when a predetermined evaluation condition is satisfied, the evaluation system comprising: acquisition means for acquiring and analysing the safety program, the safety program including a combination of function blocks FB for determining a value or values of one or more output signals in response to one or more input signals of the safety program; signal extraction means for extracting variables which are set as input signals and as output signals of the function blocks, said variables being the variables to be used for the evaluation condition; display means for displaying the extracted variable representing the one or more input signals and the associated extracted variable representing the output signals; setting screen for setting the evaluation condition, wherein the setting screen comprises receiving means for receiving from a user one or more expected values for the displayed extracted variable representing the output signals of a corresponding input variable, the expected output values being values for causing the target device to operate so as to ensure the safety of workers; the setting screen further comprises a display area for changing a value of the extracted variable representing the input signal from an initial value to a different value and for calculating a value of the extracted variable representing the corresponding output signals in accordance with the safety program; and evaluation means for evaluating the functional safety of the safety program by determining whether the calculated values of the output signals are identical to the expected output values. acquisition means for acquiring and analysing the safety program, the safety program including a combination of function blocks FB for determining a value or values of one or more output signals in response to one or more input signals of the safety program; signal extraction means for extracting variables which are set as input signals and as output signals of the function blocks, said variables being the variables to be used for the evaluation condition; display means for displaying the extracted variable representing the one or more input signals and the associated extracted variable representing the output signals; setting screen for setting the evaluation condition, wherein the setting screen comprises receiving means for receiving from a user one or more expected values for the displayed extracted variable representing the output signals of a corresponding input variable, the expected output values being values for causing the target device to operate so as to ensure the safety of workers; the setting screen further comprises a display area for changing a value of the extracted variable representing the input signal from an initial value to a different value and for calculating a value of the extracted variable representing the corresponding output signals in accordance with the safety program; and evaluation means for evaluating the functional safety of the safety program by determining whether the calculated values of the output signals are identical to the expected output values.