PROBLEM TO BE SOLVED: To provide a bone treatment system capable of shortening a treatment period by easily and quickly placing a hardened bone filling material in a treatment object bone.SOLUTION: An indwelling device 12 of a bone treatment system 10 includes: a shaft 28 formed with a lumen 32 in which a bone filling material C is distributed an indwelling balloon 22 that can be inflated with introduction of the bone filling material C via the lumen 32 and is broken to expose the bone filling material C to the inside of the bone, and a sheath 62 that can adjust the size of the indwelling balloon 22 in the inflation according to an axial position.
