Heat storage device and heat storage module including the same

A heat storage device includes: a heat storage material that absorbs or release latent heat with a phase transition between a liquid phase and a solid phase; and a heat conduction member that includes a contact surface contacting the heat storage material. The heat conduction member has a thermal conductivity higher than a thermal conductivity of the heat storage material. The contact surface includes an upstream region and a downstream region that is located at downstream side of the upstream region in a flowing direction of a heat medium. A wettability of the contact surface with respect to the heat storage material is higher in the downstream region than in the upstream region.