An object of the present invention is to provide a bone opening device capable of performing an operation of inserting an artificial bone into an incision portion of a bone more quickly and easily than before. A first blade having a pair of first long bodies whose tip portions are rotatably connected to each other and an angle adjusting member for adjusting a rotation angle between the first long bodies. A second blade having a pair of second elongated bodies that are arranged in parallel to the first blade and whose tip portions are rotatably connected to each other； and the pair of first elongated bodies, Is attached to the first long body of one of the pair and the second long body of one of the pair of second long bodies in a detachable manner. A first connecting member that connects the scale body and the one second long body and regulates the positional relationship between each other, and the other second length of the pair of second long bodies A second connecting member that is provided in the scale and connects the other first elongated body and the other second elongated body and regulates the positional relationship between them. A bone opening device provided with a first mounting state in which the first connecting member is mounted and a second mounting state in which the second connecting member is mounted as the angle adjusting member. In conjunction with the adjustment of the rotation angle between the first elongated bodies, the rotation angle between the second elongated bodies is adjusted to the same angle as the rotation angle. The second connecting member is located at the most proximal end of the second blade, and the second blade is a pair of second long bodies of the second blade. A bone opening instrument characterized in that it does not have a mechanism for adjusting the rotation angle. [Selection] Figure 1【課題】本発明の目的は、骨の切開部に人工骨を挿入する手術を従来よりも迅速かつ容易に行なうことができる開骨器具を提供することにある。【解決手段】先端部同士が回動可能に連結された一対の第１の長尺体と、前記第１の長尺体同士の回動角度を調整する角度調整部材とを有
