Curtain air bag for vehicles

A curtain air bag formed so that an auxiliary inflatable chamber adapted to reduce to as great an extent as possible a substantial decrease in a protective region of an air bag body 1 can be formed. The air bag body 1 is deployed into the interior of an automobile 8 by introducing a high-pressure gas, which is ejected from an inflator at the time of the occurrence of collision of the automobile 8 with something, into the interior of the air bag body. An auxiliary inflatable chamber 5 defined with respect to a main inflatable chamber 3 is obtained by sewing the air bag body by a substantially one sewing line using a multi-thread chain stitch method or the like. The auxiliary and main inflatable chambers 5, 3 are communicated with each other via a narrow orifice type gas flow restriction passage 6.