Abstract: A shutter assembly for a bay window to close an opening by moving a shutter curtain upward from a containing space in the bottom of the bay window and to open it by way of a downward movement of the curtain under the influence of a coil spring. The basic driving system for the shutter is located either in the roof or in the lower containing space of the bay window. Various devices are disclosed including a seal for sealing the space between the leading member of the curtain and the roof of the bay window, a structure for installing the driving motor, a structure for detachable connection of the driving shaft, hainging members used to raise and lower the curtain, a structure for supporting the winding drum on the driving shaft, as well as features to allow maintenance of the shutter assembly.