Some ethical aspects of automation system-design are discussed, based on a case study in power plant automation. The discussion uses the doing-good approach, i.e. pro-active approach is needed for designers and this relates to three levels of design: business level, company level and engineering level. Ethical problems for these levels are discussed and design concept of an interactive interface for engineering level, in particular, is proposed. This proposal is based on the result of philosophical review of automation and its evolutionary design approach is highly recommended.