To provide a heat exchanger, and a dual type heat exchanger capable of reducing the flow resistance of an internal fluid, while properly securing cooling performance.

The heat exchanger has a plurality of tubes 211, and one pair of header tanks 220, 230. It is provided with a pipe 240 having a passage cross sectional area almost the same as a pipe arrangement, arranged at one outer side in the laminating direction of the tubes 211, and communicated with interiors of the pair of header tanks 220, 230, and a partition part 250 arranged in a boundary between the tube 211 and the pipe 240 in one header tank 220, and having an opening 251 becoming predetermined resistance when the fluid passes. An inflow part 261 is communicated with one of a space in a tube 211 side or a space in a pipe 240 side with respect to the partition part 250 in one header tank 220, and an outflow part 262 is communicated with the opposite side.