To provide a buckle falling-in preventive structure used for a rear seat of an automobile in a place capable of omitting even a falling-in preventive means, capable of preventing slipping-out while easily fitting a buckle with a simple constitution, and capable of holding its buckle in its slit in a proper storage state without falling inside the buckle storage slit of a seat cushion even if its buckle is pushed from above.

A string 11 is composed of a slender string material of extremely reducing an elongation in the length direction, and is sewn on the skin 25 by both string ends 12 and 13 in an opening 30 of the buckle storage slit 27 opened in a proper place of a seating surface 26 of a rear seat cushion 21 by bending by folding back, and its anchor belt 41 is inserted into its slit 27 by twisting by inserting its buckle 44 of an anchor belt 41 with the buckle, and its buckle 44 is held in its slit 27.