Tactile characters aid in providing information to visually impaired persons. The Japanese Standards Association enacted basic design methods for embossed tactile patterns in March 2011. However, data on the appropriate size of tactile alphabets are not necessarily enough available. The purpose of this study was to evaluate the influence of the size of a tactile alphabet on identification and to investigate the perceptible size for people without rich tactile experiences. The participants of this study were 15 young people and 15 old people who were unfamiliar with tactile characters intended for visually impaired people. They were asked to discriminate tactile alphabets of six different sizes by using their forefingers without the aid of eyesight. The results showed that the younger and older participants were able to discriminate the presented stimuli faster and more accurately as the stimulus size was increased. Concretely, when the size was 28 mm, each participants regardless of young or older groups could identify the tactile character accurately and quickly. In addition, a trend was seen in that the older group needed larger tactile alphabet sizes than the younger group. We determined the relationship between the tactile alphabet size and discrimination ability of younger and older people without rich tactile experiences.