An airbag of a head-protecting airbag device includes a bag body and a connecting member. The bag body includes a general inflatable portion and a terminal inflatable portion adjoining the general inflatable portion and located at a terminal region in a front and rear direction of the bag body. The connecting member is disposed over an outboard side of the terminal inflatable portion and includes at the leading end a mounting portion to be secured to a periphery of a vehicle window. The root end of the connecting member is jointed to a closed portion of the bag body at least by two jointing points disposed away from each other in an up and down direction. The jointing points are generally equally distant from the mounting portion.