A shaft connection structure for a steering device for a vehicle, comprising: a shaft having a tightened shaft portion at its tip end portion and an annular bolt engagement groove (51 a1) on the axially intermediate portion of the tightened shaft portion; a coupling member having a tightened portion formed with a shaft insertion hole (42b2), into which the tightened shaft portion of the shaft can be inserted, and a bolt insertion aperture (42b3) provided to cross a part of the shaft insertion hole (42b2) at the tightened portion; and a bolt which is insertable into the bolt insertion aperture (42b3) of the coupling member, and said bolt is tightened upon insertion into the bolt insertion aperture (42b3), wherein the tightened shaft portion of the shaft and the tightened portion of the coupling member are coupled with each other such that a required torque can be transmitted therebetween by inserting the tightened shaft portion of the shaft into the shaft insertion hole (42b2) of the coupling member, and inserting the bolt into the bolt insertion aperture (42b3) of the coupling member and the bolt engagement groove (51 a1) of the shaft and tightening the bolt in the condition that the bolt engagement groove (51 a1) of the shaft and the bolt insertion aperture (42b3) of the coupling member are axially aligned with each other; and an insertion restriction portion having a diameter smaller than that of the tightened shaft portion is provided at the tip end of the tightened shaft portion of the shaft for restricting the insertion of the bolt through the bolt insertion aperture (42b3) of the coupling member in the condition that the insertion restriction portion axially overlaps the bolt insertion aperture (42b3) of the coupling member when the tightened shaft portion of the shaft is inserted into the shaft insertion hole (42b2) of the coupling member, characterized in that the insertion restriction portion can be rotated relative to the shaft by a set torque smaller than the required torque, even when the insertion restriction portion provided at the shaft and the coupling member are coupled with each other such that the required torque can be transmitted therebetween. a shaft having a tightened shaft portion at its tip end portion and an annular bolt engagement groove (51 a1) on the axially intermediate portion of the tightened shaft portion; a coupling member having a tightened portion formed with a shaft insertion hole (42b2), into which the tightened shaft portion of the shaft can be inserted, and a bolt insertion aperture (42b3) provided to cross a part of the shaft insertion hole (42b2) at the tightened portion; and a bolt which is insertable into the bolt insertion aperture (42b3) of the coupling member, and said bolt is tightened upon insertion into the bolt insertion aperture (42b3), wherein the tightened shaft portion of the shaft and the tightened portion of the coupling member are coupled with each other such that a required torque can be transmitted therebetween by inserting the tightened shaft portion of the shaft into the shaft insertion hole (42b2) of the coupling member, and inserting the bolt into the bolt insertion aperture (42b3) of the coupling member and the bolt engagement groove (51 a1) of the shaft and tightening the bolt in the condition that the bolt engagement groove (51 a1) of the shaft and the bolt insertion aperture (42b3) of the coupling member are axially aligned with each other; and an insertion restriction portion having a diameter smaller than that of the tightened shaft portion is provided at the tip end of the tightened shaft portion of the shaft for restricting the insertion of the bolt through the bolt insertion aperture (42b3) of the coupling member in the condition that the insertion restriction portion axially overlaps the bolt insertion aperture (42b3) of the coupling member when the tightened shaft portion of the shaft is inserted into the shaft insertion hole (42b2) of the coupling member, characterized in that the insertion restriction portion can be rotated relative to the shaft by a set torque smaller than the required torque, even when the insertion restriction portion provided at the shaft and the coupling member are coupled with each other such that the required torque can be transmitted therebetween.