Thk Co., Ltd.

Mika Oki

Wataru Saito

Yoshihiro Kudo

Tomofumi Ohashi

Takuya Miyazaki

Sho Iwashiro

Bin Zhao

The ball screw device includes: a screw shaft having an N number (N is an integer equal to or larger than 2) of rolling grooves having the same lead; balls configured to roll in the rolling grooves; and a nut member, which is assembled to the screw shaft through intermediation of the balls, and includes one or a plurality of endless circulation paths configured to circulate the balls around the screw shaft. Each of the endless circulation paths of the nut member includes: an N number of load portions, which are configured to allow the balls to roll thereon while bearing a load, and correspond to the N number of rolling grooves, respectively; and an N number of no-load portions, which each couple adjacent ones of the load portions, and are configured to allow the balls to move between the N number of rolling grooves.

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Tokyo, Japan

Mika Oki