Keeping trust at proper level is important for the appropriate use of the automation system such as an autopilot of aircraft. In recent years, advances of automation systems are attracting attention in the field of work environment and daily life. Studies on trust in automation have been based on studies of trust between human and human, and means of questionnaire, human behavior analysis and biometric data analysis technics are used to measure trust in automation. In the future, it is anticipated autonomous systems with artificial intelligence developed by advanced machine learning technology will be used in various fields including autopilot system, and the capability to provide comprehensible explanation of the outcome to users will be significant to realize the trustworthy autonomous system.