The purpose of this research is to make a quantitative analysis of Iaido (the Japanese art of using the Japanese sword) proficiency with multivariate data analysis. We carried out experiments of motion capture on Kirioroshi (a straight overhead slash) movement of Roppon-me (a sword thrust using two hands) in Iaido. We can analyze the proficiency of an Iaido practitioner by conducting PCA (Principal Components Analysis) and cluster analysis of parameters of body movement. In addition, it is expected that our research will help Iaido practitioners and masters with Iaido training through giving new information on Iaido movements.