To provide an information display instrument serving as a mark display instrument, instruction display instrument, or name display instrument, which can easily be found from outside, is low in cost, and made less deteriorative even after a long period of time has passed.

A band body 110 of an information display instrument 100 has an end part and a central part, and the central part is provided with an information carrier portion. A fastener 120 has a cylindrical structure and includes an opening and a cylindrical space. The diameter of the cylindrical space is adjusted so as to be substantially the same as the outside diameter of the band body 110 inserted inside. A friction adjustment structure is provided such that the diameter of a ring is held by applying frictional force thereto, thereby restraining movement of the band body 110 and the diameter of the ring can be changed by allowing the movement of the band body 110 when force exceeding the frictional force is applied to the band body 110. The ring is formed from the band body 110 around the trunk as of a wood 200, and the end part is inserted from the opening of the fastener 120. By tightening the diameter of the ring so that it has the same diameter as the trunk, the movement of the band body 110 is stopped by the friction adjustment structure. The diameter of the ring of the band body 110 is naturally adjusted by the friction adjustment structure according to the growth of the tree.