A
heat exchanger according to the present invention comprises a heat exchange portion in which heating medium flow paths, where a heating medium flows through a space between a plurality of plates, and
combustion gas flow paths through which a
combustion gas combusted in a burner flows are adjacently and alternatingly formed, wherein the heat exchange portion comprises a
sensible heat portion, which surrounds the outside of a
combustion chamber and comprises an area on one side of the plates, for heating the heating medium using the
sensible heat of the combustion gas generated by combustion of the burner, and a
latent heat portion, which comprises an area on the other side of the plates, for heating the heating medium using the
latent heat of water vapors in the combustion gas which has completed heat exchanging in the
sensible heat portion, wherein a connection passage for the heating medium is formed between the sensible heat portion and the
latent heat portion, the latent heat portion comprises a heating medium inlet through which the heating medium is introduced, and a plurality of latent heat portion heating medium flow paths which are formed between the plurality of plates and communicate with the heating medium inlet in parallel, and wherein the sensible heat portion comprises a heating medium outlet through which the heating medium is discharged, and a plurality of sensible heat portion heating medium flow paths which are formed between the plurality of plates and are connected serially between the latent heat portion heating medium flow paths and the heating medium outlet.