The world economy has suffered great damage due to the COVID-19 pandemic. China and North Korea enforced some strict infection control measures and 'zero-COVID strategy' is adhered, which limits human behavior including interactions. Although Japan is a little loosely regulated, the economic situation is becoming tougher and Japan is turning to a 'living with COVID strategy', which is adopted in Western countries. Also, accepting measures of visitors for sightseeing purposes are being relaxed in Japan to avoid becoming a tourism isolated country. It is important that the trade volume does not stagnate more than anything. The following questionnaire survey is being conducted with foreigners entering Japan, namely choosing one of three categories (sightseeing, business, others) as the visiting purpose. The relationship between the number of visitors who chose the business-category as the visiting purpose and the total trade is examined in this paper. As a result, it is recognized that there is a relationship, except when COVID-19 is widespread, and also there is especially a correlation between the number of visitors for business from China, USA, Taiwan and Thailand (except for South Korea) and the total trade of those countries, and it can be indicated using a simple linear regression. Total trade could be understood to be unaffected largely by the outbreak of infectious disease. The increase or decrease of visitors for business could be predicted using the simple regression equation in normal time.