The objective of the present invention is to obtain a hub assembly with which blood flashback can be verified more reliably, and with which reliability is improved by preventing the inflow of blood from a separating wall to a base end side. This hub assembly is provided with a hub body (9) connected to a tube from an external appliance, a hub outer casing (16) which is coupled to the hub body (9) and forms a liquid passage, a slitted separating wall (20) disposed in the liquid passage in the hub outer casing (16), a filter (25) disposed on the living body-side of the separating wall (20) to allow the passage of gas and regulate the passage of liquid, and a ventilation passage (16h) which provides communication between the liquid passage and the outside of the hub outer casing (16) by way of the filter (25), wherein an end portion of the ventilation passage (16h) on the separating wall (20) side of an opening portion facing the liquid passage is provided in a location at most 10 mm toward the distal end side relative to the distal end of the separating wall (20).
