The present invention provides a method for performing a measurement by a terminal in a wireless communications system having both a macro cell and a small cell. The method for performing a measurement includes the step of receiving CRS (Cellspecific Reference Signal) support information from the macro cell or the small cell which works as a serving cell. The CRS support information may contain the information of a cell sending a CRS causing interference. The method may include the step of receiving respectively a CRS from the macro and a CRS from the small cell. Here, a timing offset may be adjusted between the sub-frame receiving the CRS from the macro cell and the sub-frame receiving the CRS from the small cell.