An airbag for a blood pressure measuring device for fixing a cuff, including: a main sheet member which spreads in two layers forming a bag body, wherein a constricted portion is formed on the bag body, the constricted portion narrowing the air chamber with respect to the width direction, a pair of sub sheet members are disposed so as to correspond to the respective layers of the main sheet member, the sub sheet member occupying a region including at least a portion corresponding to the constricted portion, and the pair are respectively welded to the layers of the main sheet member at the constricted portion, the pair being welded to the corresponding layers of the main sheet member at a center near portion away from the constricted portion toward a center side with respect to the width direction.
