Only a little data is available so far on the prevalence of Asperger's syndrome. The prevalence that Fombonne (2003) estimated after considering six European research was 2/10,000. In Ishikawa's study (2006) conducted in Nagoya city, Japan, the prevalence of Asperger's syndrome was 56/10,000. Currently there are not strict diagnostic criteria of Asperger's syndrome and methods of investigation are not consistent in each study. Therefore the prevalence rate for Asperger's syndrome covered very wide range. Although we still don't have a precise prevalence data on Asperger's syndrome, the awareness of this syndrome emerged in these several decades tells us that further research and support for the children of Asperger's syndrome and their family are necessary.