To provide a termite-preventing tool having a same volume with that of a cylindrical form station, a large area toward the progressing direction of a termite passage and a high capturing efficiency and capable of switching a bait to a poisonous bait in a minimum irritation to the sensitive termites.

This termite-preventing tool consists of a case body buried into the ground, having a flat book case-form with a longer width as a whole, an opening in an upper surface and mesh state front and rear, left and right and bottom surfaces, and a freely attachable and detachable lid plate for covering the upper surface opening of the case body. In the case body, a plurality of bait woods are placed in one lateral row during monitoring and, on finding the termite, one or the plurality of the bait woods are switched to poisonous woods containing a slow acting insecticidal poison.