Provided is a support for a thermal transfer image-receiving sheet, capable of obtaining a thermal transfer image-receiving sheet that has favorable stability against curl and is excellent in the texture of a print surface in the case of print under the environmental conditions of high temperature and high humidity. A support for a thermal transfer image-receiving sheet according to the present invention includes a porous layer composed of a porous film, a first polyolefin resin layer, a substrate layer, and a second polyolefin resin layer that are layered in the order mentioned, in which the first polyolefin resin layer has a density of 0.93 g/cm3 or less; and the second polyolefin resin layer has a density of more than 0.93 g/cm3.