INERTIA LOCK DEVICE AND FOLDABLE SHEET

An inertia lock device comprising a receiving block (70) having a substantially U-shaped, obliquely upwardly opened receiving port (701a) for receiving the lower portion of a stand leg (1), a jaw portion (71c) projecting from a latch base (71a) to enter the receiving port through the bottom side thereof, a hook portion (71d) projecting from an upper arm (71b) into a bight, the lower side of the stand leg, which enters the receiving port of the receiving block, having a latch (71) that kicks the jaw portion to cause the hook portion to mesh with a receiving groove (91) in the stand leg and pressingly holds the lower side of the stand leg by the upper arm, the latch being eccentrically supported by a torsion coil spring (73), thereby reliably preventing the kick-up of a seat cushion (2) attending collision or the like.