To provide a rolling bearing capable of extending a lifetime with grease lubrication by more effectively discharging base oil in filled grease and stably supplying the same as lubricating oil of the bearing.

A seat 8 between outer ring covers is formed out of material having liner expansion coefficient different from that of a grease pocket forming part 9. The seat 8 between the outer ring covers and the grease pocket forming part 9 compresses volume in the grease pocket forming part 9 based on temperature change during bearing operation.