The H-infinity loop shaping method is known as one of the robust controller design methods. In this method, the design procedure consists of two steps: the weight design and the derivation of a controller. The controller is derived for the weighted plant to suppress the H-infinity norm of the transfer matrix consisting of a sensitivity function, a complementary sensitivity function, and so on. Therefore, the closed-loop system achieves good tracking and robustness. However, there is only a guideline for the weight design, and an explicit design index of the weight has not been given. As a result, a time-consuming and tedious process is often required to tune the weight. This paper provides a new weight design method for a stable single-input single-output (SISO) plant. The resulting weight guarantees the upper bound of the performance level before the controller design. This means that the controller design and the weight design are completely separated in contrast to the Lanzon's work. Moreover, the weight is designed using only frequency responses. Accordingly, we can avoid the process of the system identification and reduce the conservativeness caused by an overestimate of the system uncertainty. (C) 2016 Wiley Periodicals, Inc.