The objective of this paper is to overview people's sense of trust as it is reflected in the response data of questionnaire surveys. I will study the variability of people's trust systems in order to explore which aspects of their sense of trust are stable over many decades and which aspects are variable under the longitudinal changes of economical and political conditions. To begin with, I will explain briefly the history of our longitudinal and cross-national survey research on national character. Secondly, I will summarize some aspects of people's sense of trust in our longitudinal survey of Japanese national character. Thirdly, I will present cross-national comparative analysis of trust in our seven-country survey. Fourthly, I will consider the acculturation of the Japanese immigrants in Brazil, Hawaii, and the West Coast of USA. Finally, I will provide some comments for our future research.