To provide an artificial fish reef for producing the surface of the artificial fish reef, for suppressing alkaline elution, releasing slowly a mineral contributing to seaweed bed formation, and promoting adhesion of seaweeds, in the concrete artificial fish reef.SOLUTION: In a surface modification method of an artificial fish reef, an alkaline elution suppression material of phosphate cement (phosphoric acid cement) having lower pH than Portland cement is coated on the surface of a concrete artificial fish reef, and, in addition, a mineral sustained release material and/or a seaweed adhesion improvement material are also coated thereon, to thereby release slowly a mineral such as iron contributing to seaweed bed formation, while suppressing alkaline elution, and to facilitate adhesion of planospore or fertilized eggs onto the surface of the fish reef.SELECTED DRAWING: Figure 1【課題】コンクリート製人工魚礁において、アルカリ溶出を抑制し、藻場形成に資するミネラルを徐放し、藻類の着生を促進する、人工魚礁の表面を作製した、人工漁礁の提供。【解決手段】コンクリート製人工魚礁の表面にポルトランドセメントより低ｐＨのフォスフェートセメント（リン酸セメント）のアルカリ溶出抑制素材を被覆することに加えて、ミネラル徐放性素材及び／又は藻類付着性向上素材で被覆して、アルカリ溶出を抑制しつつ、藻場形成に貢献する鉄分等のミネラルを徐放させ、魚礁の表面に遊走子や受精卵が着生しやすくする人工魚礁の表面改質方法である。【選択図】図１
