Disclosed is a heat transport medium to be transported with a fluid that is liquid in an operating temperature range containing a porous material and a latent heat storage material penetrated in the pores of the porous material, wherein the latent heat storage material is incompatible with the fluid and has a melting point within the operating temperature range, and the porous material has a liquid repellency to the fluid, an affinity for the latent heat storage material, and a sponge hardness of not more than 50. This invention achieves stable heat transport with a high heat conversion efficiency even by circulating the medium through a pipeline over a long period of time. The porous material has an apparent density of about 0.05 to 0.5 g/cm3.