To provide a heat exchanger properly preventing interference of an extended tubular body section with a spiral tubular body section by a simple means even when clearance gaps among a plurality of loop sections of the spiral tubular body section of the heat transfer tube are significantly reduced.

In this heat exchanger HE, the spiral tubular body section 4 of the heat transfer tube T1 is constituted by arranging the plurality of loop sections 40 having horizontal sections and inclined sections in a state of being connected in series at intervals in the vertical height direction, the extended tubular body section 5 of the heat transfer tube T1 is connected to the horizontal section of the first loop section 40a positioned at an uppermost or lowermost stage of the plurality of loop sections 40, roughly horizontally extended, and penetrated through a side wall section 70c of the casing 7 at a roughly rectangular intersecting angle. In the spiral tubular body section 4 of this heat exchanger HE, a vertical arrangement pitch P2 between the first loop section 40a and the second loop section 40b adjacent thereto is larger than the vertical arrangement pitch P1 of the plurality of other loop sections 40.