An indwelling assembly includes an inner needle having a sharp needlepoint at a distal end to puncture a blood vessel of a patient, an inner needle hub fixed to the proximal portion of the inner needle, a hollow elongated outer member in which the inner needle is positioned, with the hollow elongated member being movable in a distal direction relative to the inner needle after puncturing the patient's blood vessel, an outer member hub fixed to the proximal portion of the hollow elongated outer member, an elongated contact member configured to contact an intermediate portion of the hollow elongated outer member, and an elongated movable member movable relative to the hollow elongated outer member and the outer member hub. The elongated movable member is connected to the inner needle hub so that the inner needle hub, the inner needle and the elongated movable member move together.