An evaporator of the present invention includes an agitation vessel having a volatile component outlet and a concentrate outlet and configured to receive a raw material liquid, a heat source provided inside the agitation vessel, a liquid distributing portion provided within the agitation vessel and configured to cause the raw material liquid to flow down the heat source, and a first condenser provided on an outer circumference of the agitation vessel and configured to cool an inner wall of the agitation vessel. The evaporator of the present invention is useful in, for example, the concentration of various liquid chemicals and chemical products and the removal of volatile impurities from these chemicals and chemical products.