To provide a floor cabinet for modular kitchen which is not affected by an uneven floor or facilitates piping or wiring.

A supporting structure of a first floor cabinet 3 includes a pair of left and right side plates 37 and 39, an intermediate plate 41 disposed between the pair of left and right side plates 37 and 39, and a back plate 43 disposed behind the pair of left and right side plates 37 and 39 and intermediate plate 41. The back plate 43 is formed such that the back plate has an upper end edge mounted to be at a height the same as the upper end edges of the side plates 37 and 39 and intermediate plate 41 but the back plate 43 has a length in the height direction is smaller than the lengths in the height direction of the side plates 37 and 39 and intermediate plate 41, the back plate 43 has a lower end edge positioned above the lower end edges of the side plates 37 and 39 and intermediate plate 41, i.e., above the floor 45, and a space 47 is held between the lower end edge of the back plate 43 and the floor 45.