To provide an evaporating concentrator which can be compactly manufactured at a low cost and in which effective evaporating concentration can be performed without leaking a malodor to the outside and the energy consumption can be reduced even when a liquid to be treated such as a photographic waste liquid is evaporated and concentrated and to provide a method for evaporating and concentrating photographic waste liquid.

In this evaporating concentrator constituted so that between a liquid evaporating part 100 containing a storage vessel 110 for storing a liquid to be treated and a condensing part 21 for liquefying vapor evaporated in the liquid evaporating part 100, a circulating route L is formed and also in the circulating route L, a flow of gas is generated through an air blowing means 230, an auxiliary means formed by coaxially arranging plural metal plates 113-1 in parallel at prescribed intervals is constituted so that it is made to reciprocatively move or circulatively move in the parallel direction with the metal plates 113-1 and charging discharging for the liquid to be treated in the storage vessel 110 are repeatedly performed and also a heating means H for heating the liquid stored in the storage vessel 110 is provided.