A rear-wheel drive shaft (1) includes a fixed type constant velocity universal joint (3), a plunging type constant velocity universal joint (2), and an intermediate shaft (4) coupling both the constant velocity universal joints to each other. A ratio (PCDBALL(f)/DBALL(f)) of a pitch circle diameter (PCDBALL(f)) of balls (33) of the fixed type constant velocity universal joint (3) to a diameter (DBALL(f)) of each of the balls (33) is set from 3.70 to 3.87. A ratio (PCDBALL(s)/DBALL(s)) of a pitch circle diameter (PCDBALL(s)) of balls (23) of the plunging type constant velocity universal joint (2) to a diameter (DBALL(s)) of each of the balls (23) is set from 3.3 to 3.6.