To attain improvement of seal performance, by returning lubricating oil by pump action of a rib, so that a return amount of the lubricating oil can be increased as large as possible, in an oil seal.

In an oil seal 2, a seal lip 5 formed by an elastic unit 4 is provided in an annular core metal 3, in this seal lip 5, a slope 5A partly brought into press contact relating to a peripheral surface of a rotary member 1 is provided, in circumferential several parts of this slop 5A, a rib 8 tilted relating to an axial line is provided, and in a part in the vicinity of one side wall surface 8A for a lubricating return guide of each rib 8, at least a tip end edge side parts of the slope 5A is formed soft as compared without a seal lip main unit part. In this way, by easily deflecting the soft part, this part is easily floated from the rotary member 1 by a dynamic pressure generated by pump action of the lib 8, and lubricating oil returned by pump action is made to easily pass through the floated part.