A dialysate extraction apparatus which can reliably perform cleaning and disinfecting on an inside of a collection port without extending a separate flow route from an on-off device. The dialysate extraction apparatus includes a dialysate extraction device having an inlet and an outlet which can circulate a liquid, and having a collection port which can collect the circulating liquid; and a cap which is attachable to and detachable from the collection port of the dialysate extraction device and which can turn on and off the collection port. When the cap is attached, the collection port defines a guide route which guides the liquid introduced from the inlet to a tip a side of the collection port, and a discharge route which discharges the liquid guided by the guide route to the outlet side.