PROBLEM TO BE SOLVED: To provide a tissue body forming device capable of improving structural accuracy in a connective tissue, while suppressing prolongation of a period when the device is embedded in environment where a biological tissue material is present.SOLUTION: A tissue body forming device 10 for forming a connective tissue body under environment where a biological tissue material is present, includes: an inner member 20 having a tissue body forming surface for forming a connective tissue body； and a cover member including a cover surface as the surface constituting an external surface of the tissue body forming device, where the cover surface covers a part of the tissue body forming surface. The cover member includes a plurality of communication parts for communicating the outside of the tissue body forming device 10 with the tissue body forming surface. Each communication part has an opening at the cover surface, where a minimum dimension of each opening in the direction along the cover surface is 0.5 mm or more and an occupancy ratio of the openings per unit area of the cover surface is not less than 20% and not more than 40%.SELECTED DRAWING: Figure 1【課題】生体組織材料が存在する環境に装置が埋設される期間の長期化を抑えつつ結合組織体における構造上の精度を高めることを可能とした組織体形成装置を提供する。【解決手段】生体組織材料が存在する環境のなかで結合組織体を形成する組織体形成装置１０であって、結合組織体を形成するための面である組織体形成面を有した内側部材２０と、前記組織体形成装置の外表面を構成する面である被覆面を備え、前記被覆面が前記組織体形成面の一部を覆う被覆部材とを備える。そして、前記被覆部材は、前記組織体形成装置１０の外側と前記組織体形成面とを連通する複数の連通部を有し、前記各連通部が前記被覆面に開口を有し、前記被覆面に沿う方向での前記各開口における最小寸法が０．５ｍｍ以上であり、前記被覆面の単位面積あたりにおける前記開口の占有率が２０％以上４０％以下である。【選択図】図１
