To enable increasing the concentration degree of finally obtained concentrate while keeping evaporated, concentrated quantity per unit time without overheating and keeping the heat balance of a heat pump circuit to stably perform evaporation concentration.

This concentrator has a second heated evaporating kettle 26 for storing concentrate 16 concentrated by a heated evaporating kettle 21 and a second heating means for heating the concentrate 16 stored in the second heated evaporating kettle 26. And between the compression part and expansion part of a heat pump circuit, a second radiation part 46 that heat is radiated from a heating medium is disposed, and the second heating means heats with the second radiation part 46 of the heat pump circuit.