The present invention relates to an artificial, undersea reef for protecting octopuses. More specifically, the artificial, undersea reef comprises: a first block consisting of a pair of first supports having a rectangular parallelepiped shape and spaced apart to face each other, and a first upper cover for connecting an upper part of the pair of supports to each other in an arc shape； a second block consisting of a pair of second supports having a rectangular parallelepiped shape and having one thereof disposed between the pair of first supports and the other thereof disposed on the outside of the first block, and a second upper cover for connecting an upper part of the pair of second supports to each other in an arc shape； a third block consisting of a pair of third supports having a rectangular parallelepiped shape and having one thereof disposed between the pair of first supports and the other thereof disposed on the opposite side of the second block which is the outside of the first block, and a third upper cover having a third upper part through-hole prepared to connect an upper part of the pair of third supports to each other in an arc shape； and an octopus propagation part prepared in the second block and the third block, respectively, wherein a second side surface through-hole through which passes an inner surface and an outer surface is prepared on a lower part of the second upper cover, and a third side surface through-hole through which passes the inner surface and the outer surface is prepared on a lower part of the third upper cover. In addition, one end and the other end of the octopus propagation part facing each other are formed in an opened jar shape, and in a state that at least a part thereof is buried in the second and third blocks, the remaining other parts are exposed into the second and third side surface through-holes.본 발명은 해중 잠재 문어 어초에 대한 것으로서, 더욱 상세하게는 직육면체 형태로 서로 마주보면서 이격된 한 쌍의 제1지지대와, 상기 한 쌍의 지지대의 상단을 아치형태로 연결하는 제1상부덮개로 이루어지는 제1블럭； 직육면체 형
