Alpha-actinin-3 is an actin-binding protein belonging to the spectrin protein superfamily. The gene expression of ACTN3 is limited to skeletal muscle, especially Type II muscle fiber which has highly force-generating capacity. This skeletal muscle-specific gene has homozygosiy for a common nonsense mutation resulting in α-actinin-3 deficiency. This deficiency does not outcome a disease phenotype. The ACTN3, However, is highly evolutionarily conserved, showing the possibility that it is redundant in humans. Researchers have suggested that this trait is related to muscle function at the extremes of mechanical-power performance. Therefore, we examined associations between the ACTN3 single nucleotide polymorphism and mechanical-power performance. For the study, we recruited 217 sprint or power elite athletes and 673 healthy adults. The results are following; Analysis of genotyping data showed highly significant differences in genotype frequencies between the groups. Mechanical-power athletes have 6.4%～14.9% of higher frequencies of RR genotype and 7.9%～12.6% of significantly lower of XX genotype than healthy adults. Also, there is differences in allele frequencies, which result in significantly higher frequencies of 577R allele and lower of 577X allele. These results suggest ACTN3 RR genotype and 577R allele are better for mechanical-power performance rather than endurance performance.