To freely insert a small article from any of vertical and longitudinal directions by forming a pocket structure out of an elastic frame, a net fitted to thereto and a plurality of fittings for securing the frame to the rear side of a back rest.

A pocket part 11 has an elastic frame body 12 formed out of elastic material such as elastic cords jointed like a close loop, and a net 15 is fitted inside the elastic frame body 12. The elastic frame body 12 and the net 15 are integrated with each other by inserting one end of the frame body 12 in net meshes 15a around the periphery of the net 15, before being jointed to each other like a close loop with a jointing member 13. In addition, a mounting piece 21 has a pair of clamping pieces 23 and 24 with a foldable hinge part 25 formed at the center, and set screws 27. The frame body 12 is clamped with a pair of the clamping pieces 23 and 24, and a plurality of the mounting pieces 21 are secured to the rear side of a backrest with set screws 27 at a plurality of positions, thereby forming the pocket part 11 on the rear side of the backrest of a vehicular seat.