To provide a heat exchanger properly simplifying a structure to prevent displacement of a spacer for a tubular body, and miniaturizing used components.

In this heat exchanger HE having a plurality of tubular body sections 50a for heat exchange, received in a casing 7 and arranged in a given direction, and a spacer S having a plurality of projecting sections 20 capable of being inserted among the plurality of tubular body sections 50a, and a basic end section 21 supporting the plurality of projecting sections 20 or connecting them in series. At least one projecting section 20 among the plurality of projecting sections 20 of the spacer S in the heat exchanger HE is an extruded projecting section 20a disposed while being extruded to an outer face side of the tubular body section 50a' positioned at the farthest point in the given direction without inserted between the plurality of tubular body sections 50a, and an engagement section engaged with the extruded projecting section 20a is disposed on the casing 7 or inside of the casing to regulate movement of the spacer S.