LUMBAR SUPPORT STRUCTURE AND SEAT STRUCTURE

The purpose of the present invention is to be suitable as a back cushioning member having a tensile structure and to reduce discomfort of a seated person. A lower lumbar support 10 installed in a lower portion of a back frame 111 and an upper lumbar support 20 installed in an upper portion of the lower lumbar support 10 are provided. Having vertically two lumbar supports 10, 20 enables a first support plate 12 of the lower lumbar support 10 to be provided so as to correspond mainly to a pelvis part where the sense of contact is hardly perceived, whereby the back cushioning member 112 having a tensile structure can be provided with a predetermined restoring force at a predetermined applicable elastic strength. Since the pelvis part located at a lower portion of a human body can be supported reliably, prevention of collapse of posture can be facilitated. Since the upper lumbar support 20 corresponds mainly to a lumbar part, by setting the upper lumbar support 20 to provide a softer springiness than the lower lumbar support 10, the sense of contact in the lumbar part is suppressed and the feeling during seating can be improved.