PROBLEM TO BE SOLVED: To provide a rail fastening device capable of increasing workability at low cost.
SOLUTION: A fastening bolt 10 is a spherical seat hexagon bolt which is a member for fastening a fastening spring 7 and has a spherical surface part 10b. In the spherical surface part 10b, the seat of the flange part of the tightening bolt 10 is formed in a projected spherical surface. A washer 11 is a member held between the spherical surface part 10b of the fastening bolt 10 and the fastening spring 7, that is, a spherical washer having a spherical surface part 11b. In the spherical surface part 11b, the surface of the washer 11 on the side in contact with the spherical surface part 10b is formed on a recessed spherical surface. Accordingly, even if the attitudes of the fastening spring 7 and the washer 11 are changed by adjusting the height of a rail 1, the fastening bolt 10 is allowed to generally uniformly abut on the washer 11 at the spherical surface parts 10b and 11b. In addition, an expensive tie plate is not required, the number of parts can be reduced, and the workability can be improved.