The invention relates to a method and an apparatus for polishing an object by CMP with use of a polishing liquid. A change point of the temperature of a surface-to-be-polished of the object at the time of polishing is detected on the basis of information on the temperature of the surface-to-be-polished of the object, which information is obtained in advance at the time of polishing. An end point of the polishing of the object is detected on the basis of information on the change point. The object and a reference object are interlocked and simultaneously polished by a common polishing body, the degree-of-polishing of the reference object is monitored, and the degree-of-polishing of the object is detected on the basis of the degree-of-polishing of the reference object.