PROBLEM TO BE SOLVED: To provide means that can form and maintain a habitat of aquatic organisms simply and effectively at low cost.SOLUTION: A biological habitat forming structure A is provided by filling gravel or gravel-like filling materials 2 and multiple cylindrical members 3, 3 in a basket body 1 with the entire surface substantially closed up by a net member 11. When the biological habitat forming structure A is installed in a water area or a land area, organisms can effectively utilize an inner space portion 31 of the cylindrical members 3 as habitats, etc. Also, a ratio of the space in the basket body 1 can be greatly improved, and air and water flow easily reach even between the filling materials 2 disposed in a center part R1 and a bottom part R2 etc. of the basket body 1.【課題】簡易、低廉かつ有効に水生生物の生息場を形成・維持できる手段の提供。【解決手段】網状部材１１によって全面が略閉塞された籠体１内に、石礫又は石礫様の中詰材２及び複数の筒状部材３、３が充填された生物生息場形成用構造体Ａ。この生物生息場形成用構造体Ａを水域又は陸域に設置した場合、生物は、筒状部材３の内空部分３１を棲み処などとして有効に利用できる。また、籠体１内における空間の割合を大幅に向上でき、籠体１内の中心部Ｒ１や底部Ｒ２などに配置された中詰材２間にも空気・水流が到達しやすくなる。【選択図】図１
