This paper overviews 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 the stability over time and the change due to the short-term changes of economic and political conditions. To begin with, I will explain briefly the history of our longitudinal and cross-national survey 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 and our East Asia 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 on cross-national scaling of trust for our future research.