To make uniformly keepable the warmth of a pizza with a comparatively large area by constituting a pizza warmth-keeping unit for delivering the pizza in a warm state by housing a resin heat reservoir in a disk-like case with a flat circular part.

A cooked warm pizza is housed in a container 2 made of an aluminum foil, etc., to be mounted on the pizza warmth-keeping unit 4 in the state of being covered similarly with an cover 3 made of an aluminum foil. The warmth-keeping unit 4 is obtained by housing a resin disk 42 in the disk- like case with a circular and flat part and the disk is constituted of a resin material obtained by blending a thermal antioxidant and a thermo-setting preventing agent to a dense polyethylene, etc. In the case of heating the pizza warmth-keeping unit 4 by a heating furnace, since the dense polyethylene is provided with a property of repeating the absorption and radiation of the heat of a stable cycle at a fixed temperature from its specific heat curve, the pizza 1 mounted on the unit 4 is warmed by heat radiation from the disk 42 during delivering to be prevented from being cooled fast.