A grease composition includes a base oil, a thickener, and an extreme pressure additive. The base oil contains trimellitate ester and poly-a-olefin. A proportion of the trimellitate ester to a total amount of the trimellitate ester and the poly-a-olefin is 10.0 mass % or more and 60.0 mass % or less. The thickener contains lithium 12-hydroxystearate and lithium stearate. A proportion of the lithium 12-hydroxystearate to a total amount of the lithium 12-hydroxystearate and the lithium stearate is 5.0 mass % or more and 95.0 mass % or less. The extreme pressure additive contains molybdenum dialkyl dithiocarbamate. A proportion of the molybdenum dialkyl dithiocarbamate to a total amount of the trimellitate ester, the poly-a-olefin, the lithium 12-hydroxystearate, the lithium stearate, and the molybdenum dialkyl dithiocarbamate is 0.6 mass % or more and 16.0 mass % or less.