To comfortably pass feces by putting the lower part of an inner periphery along the rear periphery of a Japanese-style toilet so as to form its seat and forming the height of this seat lower than the top part of a front cover of the Japanese-style toilet so as to keep a sitting posture for a long time without being tired.

A toilet seat 1 forms the lower part of its inner periphery along the rear periphery 10 of a Japanese-style toilet, namely in a U-shape by a plane view and the height of this seat 1 is set to be lowered than the top part 9 of the front cover of the Japanese-style toilet. In addition, in the seat 1, the side of the upper part of the inner periphery is formed lower than the upper part of its outer periphery 2', the front part of the seat 1 is formed lower than its front part and the width 5 of a chair part is set to be a width for stabilizing the seat. At the time of using, the inner periphery 3 of the seat 1 is placed along the rear periphery 10 of the toilet and a user places his hips on the chair part 4 to pass feces similarly to the case of a normal Japanese-style toilet. A sitting posture can be kept for a long time without getting tired by passing feces by a chair style like this.