To provide a waste fluid collector which can be mounted on and detached from a device discharging a waste liquid and prevent stain when extracting the waste fluid collector from the device.

A waste ink tank 27 which is detachably mounted on a printer including a discharge portion 97 discharging a waste ink and stores the waste ink discharged from the discharge portion when the waste ink tank is mounted on the printer includes: an ink absorbing member 45 which absorbs the waste ink; and a connection port 57 through which the discharge portion 97 is inserted or extracted when mounting or detaching the waste ink tank on or from the printer in a state where the ink absorbing member 45 is received inside a receiving space 47. The ink absorbing member 45 includes a cut-in groove 62 which, when the discharge portion 97 is inserted into the connection port 57, comes in contact with the discharge portion 97 so that the discharge portion 97 is interposed therebetween in a direction orthogonal to insertion and extraction directions.