A method of designing a control device (3, 4) configured as a set point filter type two degrees of freedom PID control system, which includes a filter into which is input a set point of a controlled variable of a plant and a first feedback controller into which is input the difference between the output of the filter and the controlled variable and that outputs a manipulated variable of the plant, and which controls the controlled variable to the set point, the design method of control device (3, 4) being characterized in that a feedback control system is equivalently converted to the set point filter type two degree of freedom PID control system, wherein the feedback control system includes a second feedback controller, into which is input the difference between the set point and controlled variable, and wherein the feedback control system includes a disturbance feedback that outputs a difference multiplied by a feedback gain, wherein the difference is between the output of a nominal plant, into which is input the output of the second feedback controller, and the controlled variable, wherein the equivalent conversion is such that a transfer function, F, of the filter and a transfer function, K', of the first feedback controller are determined according to the following Equations and, respectively, based on the feedback gain, L, a transfer function, K, of the second feedback controller, and a transfer function, P n, of the nominal plant: F = K + L P n K L + K + L P n K with F s = 1 + 1 − α T I s + 1 − β T I T D s D s 1 + T I s + T I T D s D s, and K ' = L + K + L P n K with K ' s = K P 1 + 1 T I s + T D D s wherein: the derivative time, T D, of the transfer function, F, of the filter and of the transfer function, K', of the first feedback controller is 0, the transfer function, P n, of the nominal plant is a first order transfer function, and the transfer function, K, of the second feedback controller is determined according to the following equation based on a gain, K pn, and time constant, T pn, of the nominal plant: K s = 1 + T p n s K p n s = 1 P n ⋅ 1 s wherein the first order transfer function is identified, obtaining the gain, K pn, and time constant, T pn, of the nominal plant, and the transfer function, F, of the filter and transfer function, K', of the first feedback controller are determined based on the obtained gain, K pn, and time constant, T pn, of the nominal plant, with only the feedback gain, L, as a tuning parameter, wherein as the derivative time, T d, is 0, the setting of the two degrees of freedom parameter, β, is unnecessary, and wherein the proportional gain, K p, the integral time, T 1, and the two degrees of freedom parameter, α, are given by the following equations, and, respectively: K P = K p n L + T p n K p n T I = K p n L + T p n K p n L + 1 1 − α = T p n K p n L + 1 1 T I = T p n K p n L + T p n the derivative time, T D, of the transfer function, F, of the filter and of the transfer function, K', of the first feedback controller is 0, the transfer function, P n, of the nominal plant is a first order transfer function, and the transfer function, K, of the second feedback controller is determined according to the following equation based on a gain, K pn, and time constant, T pn, of the nominal plant: K s = 1 + T p n s K p n s = 1 P n ⋅ 1 s wherein the first order transfer function is identified, obtaining the gain, K pn, and time constant, T pn, of the nominal plant, and the transfer function, F, of the filter and transfer function, K', of the first feedback controller are determined based on the obtained gain, K pn, and time constant, T pn, of the nominal plant, with only the feedback gain, L, as a tuning parameter, wherein as the derivative time, T d, is 0, the setting of the two degrees of freedom parameter, β, is unnecessary, and wherein the proportional gain, K p, the integral time, T 1, and the two degrees of freedom parameter, α, are given by the following equations, and, respectively: K P = K p n L + T p n K p n T I = K p n L + T p n K p n L + 1 1 − α = T p n K p n L + 1 1 T I = T p n K p n L + T p n