PROBLEM TO BE SOLVED: To provide a seat device which ensures a stroke of an air pack, and prevents poor appearance of a seat skin as well as reduction in durability.SOLUTION: A seat device comprises a base (21), a seat skin (22) forming a seat surface, an expansion suppression member (26) having flexibility lower than the seat skin (22), and an air pack (25) to which air is supplied and discharged from. The expansion suppression member (26) extends between the base (21) and the seat skin (22) and is coupled with the seat skin (22). The air pack (25) is provided between the seat skin (22) and the expansion suppression member (26).SELECTED DRAWING: Figure 4BCOPYRIGHT: (C)2016,JPO&INPIT【課題】 エアパックのストロークを確保するとともに、シート表皮の外観不良や耐久性の低下を防止する、シート装置を提供する。【解決手段】 基台(21)と、シート表面を形成するシート表皮(22)と、シート表皮(22)よりも低い伸縮性を有する伸張抑制部材(26)と、エアが供給及び排出されるエアパック(25)とを備え、伸張抑制部材(26)は基台(21)とシート表皮(22)との間に延在するとともにシート表皮(22)と結合され、エアパック(25)はシート表皮(22)と伸張抑制部材(26)の間に設けられる、シート装置。【選択図】 図4B