This dialysis device is configured so that residual liquid in a powder container 42 and a bypass path 51 can be drained. Accordingly, the dialysis device is provided with: a first liquid draining path 71 connecting a clean water supply path 31 to a stock solution supply path 44 on the upstream side of a liquid feed pump 33; a second liquid draining path 72 connecting the clean water supply path to a dialysate discharge path 32 on the downstream side of the liquid feed pump; and an opening path 77 allowing a branch path 43 to communicate with the outer space by opening an on-off valve 78. By opening the on-off valve of the opening path and actuating the liquid feed pump, a liquid in the powder container 42 and a liquid in the bypass path 51 can be discharged through the first liquid draining path and the second liquid draining path.