A multiple temperature system comprising: a heat supply portion configured to supply heat as heating energy or cooling energy at a first temperature via a heat medium circulating through a circulation passage; a first heat demand portion in which an on-off valve and a first indoor air-heat medium heat exchanger are connected in series by piping and to which heat is supplied via the heat medium; and a second heat demand portion in which a second indoor air-heat medium heat exchanger is mounted on a branch passage branched from the circulation passage and to which heat is supplied via the heat medium, wherein the first heat demand portion and the second heat demand portion are connected in parallel, the first heat demand portion and the heat supply portion are connected in series, and the second heat demand portion and the heat supply portion are connected in series, by the circulation passage, and in the second heat demand portion, a return passage for returning the heat medium from an outlet side of the second indoor air-heat medium heat exchanger to an inlet side of the second indoor air-heat medium heat exchanger is formed so as to be joined into the branch passage, and a return passage pump whose rotation speed is changeable by adjusting is mounted on the return passage, the heat medium at the outlet side of the second indoor air-heat medium heat exchanger and the heat medium at the first temperature are joined and the joined heat medium is supplied to the inlet side of the second indoor air-heat medium heat exchanger, and characterized in that the multiple temperature system is configured to perform a control such that the heat medium supplied to the second indoor air-heat medium heat exchanger is maintained at a desired second temperature which is lower than the first temperature when the heating energy is supplied from the heat supply portion and which is higher than the first temperature when the cooling energy is supplied from the heat supply portion by changing only the rotation speed of the return passage pump through the adjusting to control a flow rate of the heat medium on the return passage. a heat supply portion configured to supply heat as heating energy or cooling energy at a first temperature via a heat medium circulating through a circulation passage; a first heat demand portion in which an on-off valve and a first indoor air-heat medium heat exchanger are connected in series by piping and to which heat is supplied via the heat medium; and a second heat demand portion in which a second indoor air-heat medium heat exchanger is mounted on a branch passage branched from the circulation passage and to which heat is supplied via the heat medium, wherein the first heat demand portion and the second heat demand portion are connected in parallel, the first heat demand portion and the heat supply portion are connected in series, and the second heat demand portion and the heat supply portion are connected in series, by the circulation passage, and in the second heat demand portion, a return passage for returning the heat medium from an outlet side of the second indoor air-heat medium heat exchanger to an inlet side of the second indoor air-heat medium heat exchanger is formed so as to be joined into the branch passage, and a return passage pump whose rotation speed is changeable by adjusting is mounted on the return passage, the heat medium at the outlet side of the second indoor air-heat medium heat exchanger and the heat medium at the first temperature are joined and the joined heat medium is supplied to the inlet side of the second indoor air-heat medium heat exchanger, and characterized in that the multiple temperature system is configured to perform a control such that the heat medium supplied to the second indoor air-heat medium heat exchanger is maintained at a desired second temperature which is lower than the first temperature when the heating energy is supplied from the heat supply portion and which is higher than the first temperature when the cooling energy is supplied from the heat supply portion by changing only the rotation speed of the return passage pump through the adjusting to control a flow rate of the heat medium on the return passage.