A torque transmission unit comprising: a torque transmission shaft formed to have a hollow shape and including outer diameter side through-holes formed concentrically to each other and in a radial direction at two positions of one edge on sides opposite to each other in the radial direction; a torsion bar inserted into an inner diameter side of the torque transmission shaft and including a inner diameter side through-hole formed in the radial direction at a position aligned with the outer diameter side through-hole on the one edge; a connecting pin inserted into the outer diameter side through-hole and the inner diameter side through-hole in a state of being laid across between the outer diameter side through-hole and the inner diameter side through-hole; a yoke including a base portion having a discontinuous portion at one place in a circumferential direction and having a partially cut cylindrical shape, the base portion having a pair of flange portions (34a, 34b) formed at a position where the discontinuous portion is pinched and a pair of mounting holes formed at positions aligned with the pair of flange portions (34a, 34b); and a bolt inserted into or screwed with the mounting hole and narrowing a width of the discontinuous portion in a state where the base portion of the yoke is externally fitted into the one edge of the torque transmission shaft such that the base portion is coupled with and fixed to the one edge of the torque transmission shaft, wherein a state where the connecting pin is laid across between at least one of the outer diameter side through-holes and the inner diameter side through-hole is maintained by an axial displacement of the connecting pin with respect to the outer diameter side through-hole and the inner diameter side through-hole being regulated based on an engagement between both edges of the connecting pin and a displacement-regulating portion which is a part of the yoke or the bolt characterized in that a width dimension (W 33) of the discontinuous portion of the base portion is smaller than a diameter dimension (D 22) of the connecting pin and one edge of the connecting pin is present at a position visible through the discontinuous portion from the outside of the yoke. a torque transmission shaft formed to have a hollow shape and including outer diameter side through-holes formed concentrically to each other and in a radial direction at two positions of one edge on sides opposite to each other in the radial direction; a torsion bar inserted into an inner diameter side of the torque transmission shaft and including a inner diameter side through-hole formed in the radial direction at a position aligned with the outer diameter side through-hole on the one edge; a connecting pin inserted into the outer diameter side through-hole and the inner diameter side through-hole in a state of being laid across between the outer diameter side through-hole and the inner diameter side through-hole; a yoke including a base portion having a discontinuous portion at one place in a circumferential direction and having a partially cut cylindrical shape, the base portion having a pair of flange portions (34a, 34b) formed at a position where the discontinuous portion is pinched and a pair of mounting holes formed at positions aligned with the pair of flange portions (34a, 34b); and a bolt inserted into or screwed with the mounting hole and narrowing a width of the discontinuous portion in a state where the base portion of the yoke is externally fitted into the one edge of the torque transmission shaft such that the base portion is coupled with and fixed to the one edge of the torque transmission shaft, wherein a state where the connecting pin is laid across between at least one of the outer diameter side through-holes and the inner diameter side through-hole is maintained by an axial displacement of the connecting pin with respect to the outer diameter side through-hole and the inner diameter side through-hole being regulated based on an engagement between both edges of the connecting pin and a displacement-regulating portion which is a part of the yoke or the bolt characterized in that a width dimension (W 33) of the discontinuous portion of the base portion is smaller than a diameter dimension (D 22) of the connecting pin and one edge of the connecting pin is present at a position visible through the discontinuous portion from the outside of the yoke.