[Problem] To provide a hemostatic instrument: that has an expansion part that can be expanded without the use of a separate dedicated instrument； that can reduce wearer discomfort； and that can prevent unintended excessive compression of a hemostasis target site. [Solution] A hemostatic instrument 10 that comprises: a belt 20 that is to be wound around a limb W； a fixing means 30 that fixes the belt when the belt has been wound around the limb； an expansion part 40 that expands as a result of a gas being injected thereinto； a housing space 70a that can house the gas； an injection part 70 that can inject gas that is housed in the housing space into the expansion part； and a flow path 80 that allows the expansion part and the injection part to communicate. The flow path comprises a backflow prevention mechanism 82 that prevents gas from flowing out from the expansion part. The injection part is arranged upon the belt and comprises holes 70b, 70c: that pass through the injection part in a direction a2 that intersects a perpendicular X1 to the region of the belt on which the injection part is arranged； and that communicate with the housing space.
