Abstract: A window comprising: at least a pair of left and right connection attachments for mounting a window frame thereof which are fixedly secured to two mutually adjacent portions of an external wall of a building; at least a pair of left and right pivotable members whose inner ends are pivotally mounted on the connection attachments, respectively, such that they may be swung freely about their respective pivotal axes, and whose outer ends are integrally formed in their respective engaging pieces; at least a pair of left and right engaging members each having an engaging recess formed therein and which opens so as to be detachably engaged with each of the engaging pieces of the pivotable members; and a panel adhesively bonded along at least inner left and right vertical margins thereof onto the outer surfaces of the engaging members, respectively. The window is arranged such that upon mounting the panel, each of the engaging pieces is fitted sufficiently in each of the engaging recesses.