To provide a low-cost disposable toilet seat to be folded for portable use and easily installed for general household use by forming a plurality of cutting lines in the center and setting the entire shape of an outer line connecting the outer end parts of these cutting lines roughly coincident with the inner diameter of the toilet seat.

A toilet seat 1 includes a plurality of cutting lines 4 roughly at equal intervals from a perforation formed elliptically in the center toward the center, and a roughly triangular drooping part 5 and a roughly square drooping part 6 are formed by parts surrounded with these cutting lines 4 and the perforation. For use, the toilet seat 1 is positioned in the upper part of a toilet and the drooping parts 5 and 6 folded downward from the perforation 3 by gravity are guided by the peripheral edge of a large diameter window part formed in the center of the toilet 2 to be fixed to the toilet. After evacuation, water for discharging is flushed, then the drooping part 6 is pulled to the drain hole direction by the water and the entire toilet seat 1 is discharged out from the drain hole together with excrement.