A indwelling needle includes an outer needle, an outer needle hub with a flow path communicating with the inside of the outer needle and configured to connect a connector to the flow path, and a valve mechanism which opens and closes the flow path. The valve mechanism includes a valve element in the middle of the flow path having an openable/closable opening/closing section and an operation member having a side hole and configured to open and close the opening/closing section. The valve mechanism is positionable in a state in which the operation member penetrates through the opening/closing section to protrude therefrom and the side hole is located closer to the front end side than the opening/closing section. When infusion liquid is supplied in this state, the liquid flows to the flow path through the side hole and the dead space within the flow path is filled with the infusion liquid.
