Heat storage unit and heat storage module using same

A heat storage unit (100) immersed in a heat medium, wherein the heat storage unit (100) is provided with: heat storage elements (10) that undergo reversible phase changes between liquid and solid phases in accompaniment with the generation or absorption of latent heat; and heat-conducting elements (20) disposed so as to be in contact with the heat storage elements (10), contact surfaces that are in contact with the heat storage elements (10) having higher wettability, in relation to the the heat storage elements (10), on the downstream side of the heat medium than on the upstream side, and the heat-conducting elements (20) having higher heat conductivity than the heat storage elements (10).