An indwelling needle assembly includes a hollow outer needle, an outer needle hub fixed to a proximal portion of the outer needle, and an inner needle inserted in the outer needle. An inner needle hub is fixed to a proximal portion of the inner needle. A pressing member is connected to the outer needle hub, wherein the pressing member presses a portion of the outer needle between a proximal end and a distal end during a puncturing operation. The needlepoint of the inner needle and a distal portion of the outer needle, while in an assembled state, puncture a blood vessel in a process of placing the outer needle indwelling in a blood vessel.