the conventional structure shown in fig9 are denoted by the same reference symbols as in fig9 and descriptions thereof are omitted a drainage capability of a side flow type parallel flow heat exchanger 1 can be improved by forming the parallel flow heat exchanger 1 to have a structure shown in fig1 that is in the parallel flow heat exchanger edges of corrugated fins 6 at a surface of the heat exchanger on a side thereof where condensate water gathers protrude from edges of flat tubes 4 a water guide member 10 is inserted into a gap g between every adjacent ones of protruding portions of the corrugated fins 6 a distance between the water guide member 10 and the protruding edge of that one of the corrugated fins 6 which is situated above the water guide member 10 is such that surface tension of water is allowed to act therebetween as the water guide member 10 any of the following can be used for example various types of water absorbent and non water absorbent members allowing surface tension of condensate water to act on them which include an assembly of fibers preferably synthetic fibers namely a so called cord a member formed by twisting wires or synthetic resin filaments into the shape.