Disclosed herein is a medical elongated body including: a first channel through which a first liquid flows a second channel through which a second liquid different from the first liquid in liquid composition flows a mixing section at which the first channel and the second channel join and in which the first liquid and the second liquid are mixed a gas channel through which a gas flows a gas mixing-in section adapted to mix the gas into at least one of the first liquid flowing through the first channel and the second liquid flowing through the second channel or into a liquid mixture formed by mixing in the mixing section a foaming member adapted to convert the liquid containing the gas mixed therein to a foamed material to be discharged and a discharge port through which the foamed material to be discharged is discharged.
