To provide drainage equipment of a building, which enables the suitable performance of a maintenance operation of a drainage passage member.

The building is constructed from a plurality of building units including a building unit 20a constituting a bathroom 15 and an undressing room 16. A bathtub 38 and a bathroom floor pan 37 are provided adjacently to each other in the bathroom 15; and a floor surface of the bathroom floor pan 37 is formed above the bottom of the bathtub 38. A drainage unit 50 is provided below the bathroom floor pan 37. The drainage unit 50 comprises: a storage tank 51 for storing bathtub wastewater discharged from the bathtub 38; a plurality of connecting pipes 61 and 63 which are connected to the storage tank 51; and a supporting panel 52 for integrally supporting the storage tank 51 and the connecting pipes 61 and 63. A flooring material 84 of the undressing room 16 adjacent to the bathroom 15 is provided with a maintenance window portion 83. The drainage unit 50 can move to a position below the maintenance window portion 83 in an underfloor space.