A seal ring (26) configured to be employed with a cross shaft (16) including a center section (17) and four shaft sections (18a, 18b, 18c, 18d) extending in four directions from the center section and formed with step faces (17a) where the center section widens out from base ends of the shaft sections outward in radial directions of the shaft sections, and with bearings (21) for mounting to leading end portions of the shaft sections. The seal ring is fitted over the shaft section and interposed between the bearing and the step face. The seal ring includes a seal lip (34) configured to contact the step face around the entire circumference, and an indentation (36) the seal lip enters by deforming when mounted to the cross shaft.