To remove immediately an offensive smell issued in a Western-style toilet bowl.

An appropriate number of suction holes 8 arranged along the inner peripheral edge 15 of the upper end face 1a of the main body 1 of a toilet bowl are opened in the backing plate 5 of a hollow toilet seat 2 and one end part of a discharge hose 10 is connected to the toilet seat 2, while the other end part of the discharge hose 10 is connected to a suction unit. Seating sensors 7 are fitted respectively in elastic members 6 joined to the backing plate 5 of the toilet seat 2 and being in contact with the upper end face 1a of the main body 1 of the toilet seat. The seating sensors 7 turn ON when a seating load is applied to the toilet seat 2, and the suction unit operates until an additional time passes after the seating load is removed. A smell issued in the main body 1 of the toilet bowl is sucked into the toilet seat 2 through each of the suction holes 8 and discharged outside through the discharge hose 10.