A heat exchanger includes: first layers each including first flow channels that are microchannels; and second layers each including second flow channels that are microchannels. The first layers and the second layers constitute a lamination. Heat is exchanged by performing either of: liquid evaporation in the first flow channels and gas condensation in the second flow channels, or liquid evaporation in the second flow channels and gas condensation in the first flow channels. The lamination includes: a first liquid transport pore that is in fluid communication with the first flow channels; and a second liquid transport pore that is in fluid communication with the second flow channels.