To surely and easily secure a return tube to a nut and prevent the return tube from floating and expanding when circulating failure of balls occurs. The ball screw device has a screw shaft having a helical shaft raceway groove on the outer face thereof, a nut having a nut raceway groove on the inner face so as to oppose to the shaft raceway groove, a load path formed by the shaft raceway groove and the nut raceway groove, balls rotatably mounted in the load path, a communicating member communicating both ends of the load path to guide the balls exterior of the nut and having a bent portion; a tube fixture for fixing the communicating member to the nut and a reinforcement member for receiving stress applied to the bent portion of the communicating member on an outer face of the tube fixture.