An ice maker includes an ice tray, an ejector configured to rotate with respect to the ice tray and cause rotation of ice pieces, and a motor configured to drive the ejector to rotate relative to the ice tray. The ice tray includes a first guide rib located at a lower portion of the ice tray and configured to exchange heat with cool air supplied from a cool air inlet, and a second guide rib located at the lower portion of the ice tray and arranged at a center region of the lower portion of the ice tray. The ice tray defines a first area including the first guide rib, and a second area including both of the first and second guide ribs, where the first area of the ice tray is located closer to the cool air inlet than the second area.