Abstract: Provided are a grease composition and a rolling device which can prevent a decrease in seal performance even when a low-viscosity base oil having, for example, a kinematic viscosity of 5 to 40 mm2/s is used, and can achieve both seal performance and low torque. A seal member (12a) has a plurality of seal lips (114), (115), and (116) made of an elastic material, and a grease composition is sealed in gap portions (121) and (122) between a sliding surface of a slinger (106) on which the seal lips slide and the two adjacent seal lips. The grease composition contains a base oil and a polar polymer, and a weight-average molecular weight of the polar polymer is from 5000 to 140000.

Abstract: A crown type cage for a ball bearing includes an annular main portion, a plurality of pillar portions protruding in an axial direction from the main portion at predetermined intervals in a peripheral direction, and a spherical pocket formed between the adjacent pillar portions and capable of holding balls. The pillar portion has a pair of claw portions of which tip end portions are spaced apart from each other, and a connection portion that connects the pair of claw portions. A bottom surface of the main portion is provided with a part protruding in the axial direction.

Abstract: The present invention provides a grease composition which makes it possible to prevent deterioration in sealing properties even when base oil having a kinetic viscosity of as low as, for example, 5-40 mm2/s is used and which makes it possible to realize both sealing properties and a decrease in torque. The present invention also provides a rolling device. A sealing member (12a) comprises a plurality of sealing lips (114), (115), (116) each of which is made of an elastic material. A grease composition is sealed in void parts (121), (122) that are each located between a sliding surface of a slinger (106), on which the plurality of sealing lips slide, and two adjacent sealing lips. This grease composition contains base oil and a polar polymer. The polar polymer has a weight-average molecular weight of 5,000-140,000.