AbstractSelf‐tuning control (STC) is a control technique to adjust the parameter of the on‐line controller which adapts itself when plant parameter changes. Effective ways to design STC include minimum‐variance control (MVC), generalized minimum‐variance control (GMVC), and generalized predicted control (GPC). The structure of MVC and GMVC is especially easy and manageable. It is necessary to use MVC so that a plant is a minimum phase system and stable in the discrete time‐domain. But, in general the actual controlled system is in continuous time. Then, when digitizing is performed, it sometimes becomes a non‐minimum phase system. If we set the sampling time very low, an MVC controller has unstable poles. In this paper, we propose an MVC design for a plant which is stable and a minimum phase system in a continuous time domain by introducing a delta operator and weight adjustment of the cost function. Then, we evaluate its stability. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(1): 17–25, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20472