Grease composition for bearing

A composition comprising:

• an (A) thickener;
• and
• a (B) base oil,
• wherein the (A) thickener is a urea thickener represented by formula (1):
• R1NHCONHR2NHCONHR3 (I)
• where R1 and R3 each independently represent a hydrocarbon group selected from the group consisting of an (a1) monovalent chain hydrocarbon group having 6 to 22 carbon atoms;
• an (a2) monovalent alicyclic hydrocarbon group having 6 to 12 carbon atoms;
• and an (a3) monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and R2 represents an (a4) divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and
• wherein a 2×106 μm2 portion of a transmission image in a sample with an average thickness of 11 μm observed with an optical microscope at 300× magnification has a transmission-image-area ratio of an aggregation part having a transmission image area exceeding 40 μm2 relative to a transmission image area of the 2×106 μm2 portion of the sample of 15% or less.