A vehicle seat includes a seat back, a seat
cushion, and a
system for facilitating relieving of fatigue of a person sitting on the vehicle seat for many hours. The
system includes an angle sensor installed within the seat back for sensing variations in an angle of a
pelvic region of the person sitting on the vehicle seat, an active device installed within the seat back for pressure-supporting the
pelvic region of the person, an actuating device connected to the active device for actuating the active device and a
sequential control unit electrically connected to the angle sensor and the actuating device for controlling the operation of the actuating device, the angle sensor being constructed so as to send the
sequential control unit signals representing values of variations in the angle of the
pelvic region of the person, the
sequential control unit being constructed such that, when a value represented by a
signal sent to the sequential
control unit from the angle sensor is more than a predetermined value, the sequential
control unit sends the actuating device a command to actuate the actuating device, whereby the active device is actuated, to thereby control supporting pressure that is applied to the pelvic region of the person.