The common single nucleotide polymorphism (SNP) rs1360780 (C/T) of the FK506 Binding Protein 5 (FKBP5) gene has been reported to be associated with an altered response of the hypothalamic-pituitary-adrenal (HPA) axis and the development of stress-related psychiatric disorders such as posttraumatic stress disorder (PTSD). In the present study, we examined whether this SNP is associated with cognitive function in a non-clinical population. The full versions of the Wechsler Memory Scale-Revised and Wechsler Adult Intelligence Scale-Revised were administered to 742 and 627 Japanese individuals, respectively, followed by genotyping of rs1360780 by the TaqMan 5'-exonuclease allelic discrimination assay. For both cognitive tests, we found significantly poorer attention/concentration (working memory) in aged (>50 years old) individuals carrying the T allele compared with their counterparts. This finding accords with an altered HPA axis and vulnerability to stress-related psychiatric disorders.