To inexpensively renew a drain riser only on a specific floor of an apartment housing.

The drain riser 30 of this drainage apparatus comprises a socket 35 and a spigot 31s for a joint. A drain pipe joint 20 comprises an upper socket section 200 and a pipe joint body section 21. The upper socket section 200 and the pipe joint body section 21 are connectable to and disconnectable from each other. The lower end straight pipe section 225 of the drain pipe joint 20 on the upper floor is inserted and connected to the socket 35 of the drain riser 30. The spigot 31s of the drain riser 30 is inserted and connected to the upper socket section 200 of the drain pipe joint 20 on the lower floor. The inserted depth dimension of the socket 35 is so set as to move the drain riser 30 a predetermined dimension K upward from the state in which the lower end straight pipe section 225 of the drain pipe joint on the upper floor is inserted and connected. The inserted depth dimension D of the upper socket section 200 of the drain pipe joint 20 on the lower floor is set to a value smaller than the predetermined dimension K.