To provide a waste ink absorber excellent in permeability and retaining performance, a waste ink absorber to be mounted in a waste ink tank to absorb waste ink discharged from a head for ejecting ink, includes, in a state of a single piece of the waste ink absorber not mounted in the waste ink tank, a portion low in density and a portion higher in density as compared with the portion low in density in a direction along a plane surface having a largest surface area.