To provide a spline coupling to reliably prevent the occurrence of gall and seizure to a contact portion between female and male splines at the two end parts of a female spline due to its owing weight even when the owing weights of the forming shaft of the female spline and the forming shaft of the male spline are high.

Bushes made of a soft metal are situated at the two end parts of a female spline 11. By decreasing a gap S between the inside diameter surface of its bush and the large diameter outer surface 21a of a male spline 21 to a value lower than all of a gap S1 between the large diameter inner surface 11a of the female spline 11 and the large diameter outer surface 21a of the male spline 21, a gap S2 between the small diameter inner surface 11b of the female spline 11 and the small diameter outer surface 21b of the male spline 21, and a gap S3 between the tooth groove flank 11c of the female spline 11 and the tooth flank 21c of the male spline 21, direct contact between the female spline 11 and the male spline 21 at a portion where a force by the owing weights of the shafts 1 and 2 is exerted is reliably prevented from occurring.