PROBLEM TO BE SOLVED: To provide a specific antibody serving as a low-density lipoprotein-related protein 6 (LRP6) antagonist.SOLUTION: The antibody binding to the low density lipoprotein-related protein 6 (LRP6) or an antigen-binding antibody fragment thereof is provided. The antibody or the fragment thereof comprises: a heavy chain variable region CDR 1 with a specific sequence; a heavy chain variable region CDR 2 with another specific sequence; a heavy chain variable region CDR3 with another specific sequence; a light chain variable region CDR1 with another specific sequence; a light chain variable region CDR2 with another specific sequence; and a light chain variable region CDR3 with another specific sequence.SELECTED DRAWING: None【課題】低密度リポタンパク質関連タンパク質6(LRP6)アンタゴニストである特異的抗体を提供する。【解決手段】低密度リポタンパク質関連タンパク質6(LRP6)に結合する抗体またはその抗原結合抗体断片であって、該抗体またはその断片が、ある特定の配列の重鎖可変領域CDR1;別の特定の配列の重鎖可変領域CDR2;また別の特定の配列の重鎖可変領域CDR3;他の特定の配列の軽鎖可変領域CDR1;また他の特定の軽鎖可変領域CDR2;およびさらに異なる特定の配列の軽鎖可変領域CDR3を含む、抗体またはその断片。【選択図】なし