A rolling bearing system provided with an inner ring including a first raceway surface, an outer ring including a second raceway surface, a rolling element retained between the inner ring and the outer ring and capable of rolling along the first raceway surface and the second raceway surface, and a lubricant storage section incorporated in a bearing structure. The lubricant storage section includes a grease tank arranged between the inner and outer rings for storing a grease, and a grease pressing mechanism for pushing the grease stored in the grease tank out of the grease tank to supply the grease to the rolling element and the first and second raceway surfaces. The inner ring includes a first extending surface adjoining the first raceway surface, and the outer ring includes a second extending surface adjoining the second raceway surface and facing the first extending surface. The grease tank is housed in an annular space defined between the first and second extending surfaces.