PURPOSE: To suppress a height of frost, to eliminate bridging due to frost and to obviate obstruction of a gas stream by forming a cutout, etc., at an end disposed at a gas stream inlet side of a fin in a heat exchanger in which a refrigerant tube bent in a zigzag manner is connected with a plurality of fins.

CONSTITUTION: A heat exchanger to be used for an evaporator, etc., for a refrigerator, a refrigerating display case, etc., comprises many fins 1 so disposed from a dense side to a sparse side toward an upstream side of a gas stream 11, and a zigzag refrigerant tube 5 inserted perpendicularly to the fins 1 and made of a straight tube part 7 and a bent tube part. Each fin 1 is formed at a plurality of positions with a long hole 3 in which the tube 5 is inserted in such a manner that both ends of the hole 3 are as reception holes 9 for receiving the part 7. A cutout 21 is formed at a part of the end of the fin 1 at an input side of the stream 11 thereby to grow frost 13 along edges 1A, 21A having long line lengths to suppress growth of the frost 13 in a height direction.