Ways of viewing human error and approaches for system safety in the area of human interface research are reviewed with emphasizing improvement of human reliability within human-machine system. Contents dealt in this article are; three ways of human error, three different modes of information processing at human interface, GEMS dynamics model to explain dynamic character of human cognitive error, a comprehensive scheme to analyze human cognitive error, human factors view on introducing automation mechanism in the machine system, approaches for human-centered automation, human error viewed from social and organizational context, wholistic approach for system safety and the relevant method by using incident analysis reports.