To provide a ground fabric for a coated air bag produced by coating the surface of a ground fabric having high and balanced mechanical property, flame-retardance, gas impermeability, flexibility, compactness and storability with a resin elastomer, and provide a method for the production of the ground fabric.

The ground fabric for the coated air bag is produced by coating a ground fabric composed of flat cross section filaments having a flatness (ratio of the lengths of the major axis to the minor axis) of 1.5-8 with a resin elastomer. The cross-section of the ground fabric has a horizontal degree index (HI) of 0.85-1.0 and the major axis of the flat section of each filament is oriented in the horizontal direction of the ground fabric. The horizontal degree index is defined by the mean sum of the cosine (hi) of the angle (θ) between the major axis direction of each single yarn constituting the ground fabric and the horizontal direction of the ground fabric.