To provide a floor structure for a bathroom unit in which not only workability in installation work such as leveling can be improved but also preservation/transportation or carry-in work can be simultaneously facilitated and a bathtub can be inexpensively installed while having a sufficient water- proof property by turning a floor into effectively divided state.

The bathtub floor where the bathtub is arranged is composed of a frame-shaped metal frame having an opening on its upper surface side and a water-proof pan arranged in the opening on the metal frame in the form of a pail having deep bottom for housing and arranging the bathtub insides, and a washing space floor to provide a washing space is composed of a frame- shaped metal frame having an opening on its upper surface side and a water- proof pan arranged on the opening of the metal frame in the shape of a tray having a shallow bottom. Then, the water-proof pan on the bathtub side and the water-proof pan on the washing space side are linked via a linking member having a fixed part and a lock part.