To provide a stool seat system, with which a stool cover can be automatically be opened when the closing state of the stool seat and the stool cover is detected by a human body detecting sensor and the stool seat and the stool cover can automatically be closed in the state of opening the stool seat and the stool cover.

This stool seat system provided with a turnable stool seat 5, a turnable stool cover on the stool seat and a human body detecting sensor 8 is equipped with a driving mechanism 10 for varying the detecting area of the human body detecting sensor 8 correspondingly to the attitudes of the stool seat 5 and the stool cover 6. The human body detecting sensor 8 is arranged on the front side of a case 4 to be opposed to the stool seat 5 of the stool seat system.