[Object] To favorably discharge gas internally present in a device during filling of a bone filling material. [Solution] A bone treatment system 10 has a shaft 30 that has a flow path 38 which enables a bone filling material to be placed on a space 108 of a radius 100 to flow therethrough, and a filling balloon 32 that communicates with the flow path 38 in a distal portion of the shaft 30 and that is filled with the bone filling material.Furthermore, the bone treatment system 10 includes a gas discharge portion 46 that causes air (gas) inside the flow path 38 to flow in a direction toward a proximal end rather than the filling balloon 32, when the bone filling material is supplied to the flow path 38.
