To easily form slit parts which are opened and expanded according to deployment of an air bag onto the air bag, by bridging and sewing together nonwoven fabric with strength bearable to ordinary uses and breakable by the deploying pressure of an air bag between peripheries of a front cloth part and side cloth parts on the air bag module equipping side.

This post-attaching seat cover is formed into a stereoscopic form by sewing together a front cloth part 1 made by sewing together central cloth 1a to cover the seat face and right and left cloth parts 1b, 1c to cover both bank parts, side cloth parts 2 to cover right and left side parts, and a back cloth part continued from the front cloth part 1. The parts between peripheries of the front cloth part 1 and the side cloth parts 2 on the air bag module equipping side are formed to be slit by deployment of the air bag as slit parts 3. The slit parts 3 are formed not by sewing together the parts between the peripheries of the from cloth part 1 and the side cloth parts 2 but by bridging nonwoven fabric 4 between peripheries of the front cloth part 1 and the side cloth parts 2 and sewing together. The nonwoven fabric 4 has strength bearable to ordinary uses and breakable by the deploying pressure of the air bag.