With the aim of providing a basis for the improvement of physical functions needed to perform lifelong sports, this study examined center-of-gravity (CoG) sway in middle-aged females playing badminton on a regular basis. Thirty middle-aged females with experience of playing badminton were divided into 2 groups based on the volume of training per week: high- (HV) and low (LV)- volume groups. The mean ages of the groups were similar (47.7±4.9 and 47.9±4.2, respectively). To record the CoG sway path, each subject stood on a stabilometer (Anima GP-5000) for 30 seconds, adopting 3 positions: standing on two legs; and standing on one leg on the same side as the hand holding (racket) and not holding (non-racket leg) the racket. Significant differences were observed in the total trace length and outer peripheral area when standing on two legs with the eyes open or closed, as the HV showed lower values than the LV (p<0.05). These results support the effectiveness of badminton to reduce CoG sway even when played as a recreational sport by individuals in their forties or fifties, as well as the feasibility of improving the balance ability by increasing the volume of training per week.