To reduce noise of a ball screw device.

In this ball screw device provided with a screw shaft 3 having a spiral screw groove 2 on an outer peripheral surface, a ball nut 6 which has a screw groove corresponding to the screw groove 2 of the screw shaft 3 on an inner peripheral surface and is loosely fitted into the screw shaft 3 and many balls arranged to roll between both of the screw grooves and circulating by being guided by a ball circulating part 50A mounted with a ball on the ball nut 6, surrounding members 21 and 25 for surrounding the ball circulating part 50A are provided, and foamed resin 29 is filled among the surrounding members 21 and 25 and the ball nut 6.