A retainer ring configured to be attachable, at a first side thereof, to a polish head of a polish apparatus configured to polish a polish object by depressing the polish object against a polish pad is disclosed. The retainer ring is configured to depress the polish pad at a second side thereof. The retainer ring includes a contact surface contacting the polish pad. The contact surface applies depressing force on the polish pad. The depressing force is directed from a polish head side and is applied so as to be centered on an imaginary circle of pressure center having a radius falling substantially in a middle of an inner radius of the retainer ring and an outer radius of the retainer ring. An area of the contact surface is greater in a first region inside the circle of pressure center than in a second region outside the circle of pressure center.