PROBLEM TO BE SOLVED: To reduce labor required for a surgical operation for installing an artificial hip joint.SOLUTION: A surgical instrument 1 includes a stem broach 2, a cutting member 6, and an adapter 5. A fitting hole part 10 is formed in a proximal part 8a of a stem broach body 8 of the stem broach 2. The adapter 5 includes a fitting part 67 capable of being attached to/detached from the fitting hole part 10, and a support 68 that is protruded from the fitting part 67. The support 68 can support the cutting member 6 to permit a motion that makes the cutting member 6 cut an end surface of a proximal part 102c of a thigh bone 102.
