There is provided a mixing chamber that can uniformly mix a plurality of liquids. A mixing chamber (15) according to the present invention is provided on a blood circuit. A main body portion (10) has, on a side surface of a cylindrical shape, a first inlet (150) through which a liquid is introduced into a space of the cylindrical shape and a second inlet (160), and an upper space (11) is provided to extend from the first inlet (150) to a highest portion of the main body portion (10).
