Abstract: A grease composition is disclosed. The grease composition comprises: 100 parts by mass of (A) an aryl group-containing polyorganosiloxane; 1 to 50 parts by mass of (B) an acrylic block copolymer; and (C) solid particles. Component (B) has a weight average molecular weight of from 10,000 to 1,000,000 and a molecular weight distribution [ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn)] of 1.5 or less. Component (B) is present in an amount of from 1 to 40 mass % of the overall grease composition. The grease composition has excellent damping characteristics, hardly any oil separation (even at high temperatures), excellent lubricating performance, and an ability to reduce noise generated by a mechanical device when applied to a noise-generating site of the mechanical device. Sliding members, etc., to which this grease composition has been applied, are also disclosed.