To ensure a specified attachment force even when a cost reduction is contrived by reducing attachment parts of a steering member as much as possible, and at the same time, to enable the automation of the attachment work of the steering member to be achieved.

An attaching mechanism 10 attaches the steering member 1 in such a manner that the longitudinal dimension of the other end side 1b of the steering member 1 may be adjustable with one end side 1a of the steering member 1 as a reference. The attachment mechanism 10 is constituted by having an attachment flange 6 which is fixed to the other end side 1b, a project nut 11 which is fixed to the cabin side facing surface side in the attachment flange 6, a bolt 8 which is screwed with the project nut 11 by going through a car body 2 and the attachment flange 6, and a dimensional adjustment deforming section 20 which is formed on the attachment flange by a slit 20a being provided in a manner to surround the vicinity of the project nut 11. The dimensional adjustment deforming section 20 is deformed to the car body 2 side based on a general area of the attachment flange 6 by the screwing of the bolt 8 with the project nut 11, and thus, the car width directional length dimension of the steering member 1 is made adjustable.