To propose a floor framing horizontal member allowing an easy laying work of floor boards even in the construction of a floor framing with metal sectional members, and further never deteriorating the heat insulating performance of a floor.

This floor framing horizontal member 1 comprises a bar-like metal sectional member 2 having a holding part 20 having an upwardly opened groove shape, a heat insulating member 3 smaller in conductivity than the metal sectional member 2, which is mounted on the upper end of the metal sectional member 2, and a bar-like timber 4 supported in the holding part 20, the upper surface of which abuts on the lower surface of a floor board. The metal sectional member 2 comprises a U-shaped sectional groove part 5 for mounting the heat insulating member 3 and an overhang 6 horizontally protruded from the metal sectional member 2 to the outside, and it is preferably formed of an aluminum alloy-made extruded sectional member.