This paper presents a new STS (Steady-state-error and Transient Suppressions) model dc-dc converter using the reactor current and its transient characteristics. The controlled object is the reference bias in the P-I-D control and the reference value in the P control. The reference bias is controlled in both steady and transient states. The reference value is modified to suppress transient characteristics by the reference modification control. The modifying of reference value operates only when the output voltage becomes larger than a plus-minus 1% from the steady-state value, and is terminated when the undershoot of output voltage has reached the maximum value. As the result, the convergence time of output voltage is improved 96% compared with the conventional method. Furthermore, the undershoot of output voltage and the overshoot of reactor current are improved 56% and 32%, respectively.