CONNECTION STRUCTURE OF STEERING SHAFT, AND MANUFACTURING METHOD THEREOF

PROBLEM TO BE SOLVED: To easily and efficiently manufacture connection structure in an extendable part of a steering shaft having an impact absorbing function by being contracted axial-directionally. SOLUTION: This structure is composed of an inner shaft A1 having a filling circumferential groove 3 formed along a circumferential direction of a shaft, external gear-like parts 1, 1 opposed in both sides of the groove 3, and a low gear-like part 2 formed in an end in at least one side out of the opposed external gear-like parts 1, 1 to have a width equal to tooth width of each external tooth-shaped part 1a and to be low, and having its top part formed into a recessed top part, an outer shaft having an internal gear-like part 4 meshed with the external gear-like part 1, and a filling hole 5, and a synthetic resin material. The synthetic resin material is filled betweeen the internal gear-like part 4 of the outer shaft and the filling circumferential groove 3 and the low gear-like part 2 of the inner shaft A1 via the filling hole 5.