To provide a method for forming a concrete floor for low-temperature facilities, which is free from cracking or chipping in concrete, and to provide a structure of the concrete floor.

According to the method for forming the concrete floor for the low-temperature facilities, joint members 20 for partitioning at least a surface layer of a concrete floor area 1a into a plurality of polygonal regions 29, are set on the area 1a, and concrete 4 is placed in every polygonal region 29, to thereby form the concrete floor 30 together with the joint members 20. Preferably, an inside corner of a side angle portion of a concrete portion 10 inside the joint member 20 is formed into an obtuse angle, and an upper edge of the joint member 20 is formed like flares. Therefore, an upper edge corner portion of the concrete portion 10 is formed into a curved surface or a chamfered surface.