In recent years the occurrence of thiamin deficiency diseases has increased particularly among elderly people and there has been some speculation about whether or not any particular factors exist. In this study, we focused on elderly people requiring constant care in nursing homes and we conducted an accurate condition survey of total thiamin concentration in whole blood as a means of nutritional assessment. The total number of participants was 14 males and 60 females who were residing in a nursing home; they were aged between 65 and 105 y old. All of the subjects agreed to take part in our research. We conducted the following tests: anthropometric measurements, blood examination including total thiamin levels, and also physical functions such as in the level of nursing care required and tests of other physical conditions. The average±standard deviation of thiamin concentration was 22.4±8.9 ng/mL and the number of people with a deficient condition (less than 20 ng/mL) was 42, which was 56.8% of the total. From these results, the existence of thiamin deficiency is validated in more than half of the elderly people who require nursing care. On the other hand, the method of meal intake for all participants who have a thiamin deficiency was oral intake and for those who were non-deficient in thiamin, the percentage of tube feeding or nutritional supplementation intravenously was 37.5%, which was a significantly high value.