Disclosed is an apparatus for repelling birds that can be readily installed on a structure and effective in repelling birds. To fundamentally prevent the birds from perching on the structure, the apparatus for repelling birds in accordance with an embodiment of the present invention includes: a fastening means including a first supporting part, a second supporting part and a fastening part interposed between the first supporting part and the second supporting part, and having the first supporting part and the second supporting part protruded in a same direction from either end of the fastening part in such a way that a protruded structure is fitted therein; a stopper being engaged with one of the first supporting part and the second supporting part in such a way that the fastening means is fastened to the structure after the fastening means is fitted on the structure, the stopper being at least one bolt; a supporting means being installed on the fastening means; a wire having at least one end coupled to the supporting means; and a tension adjusting means being installed at a portion where the wire is coupled with the supporting means.