PROBLEM TO BE SOLVED: To provide a nest building prevention tool capable of preventing nest building by a bird such as a crow.SOLUTION: A nest building prevention tool includes a receiving tool 23 for receiving either a nest 22 between a first nest built on a first place by a bird and a second artificial nest, and a fixture for fixing the receiving tool on a second place which is different from the first place on a utility pole.COPYRIGHT: (C)2016,JPO&INPIT【課題】カラス等の鳥による営巣を防止することができる営巣防止具を提供する。【解決手段】鳥によって第1の場所で作られた第1の巣及び人工の第2の巣のうちの何れか一方の巣22を受ける受け具23と、前記受け具を電柱における前記第1の場所とは異なる第2の場所に取り付ける取付具と、を備える営巣防止具。【選択図】図2