To provide a heat exchanger having a heat transfer member and a fin, and being capable of highly efficient heat exchange (heat transfer) between the fin and the heat transfer member.

In a cross-sectional view, a heat pipe 17 is provided to protrude from a base part inner face 13a of a base part 13 in a flow channel direction (upward in the figure). That is, the depth of a groove 23 is greater than the thickness of the base part 13. In the cross-sectional view, a half or more of the whole circumference of a heat pipe 17 (D in the figure) is preferably positioned to protrude above the base part inner face 13a. This arrangement allows heat from the heat pipe 17 to efficiently transfer to a fin 15.