To provide a single window sash which forms a vertical band window mounting therein windows of different types, such as fixed windows and double sliding windows, without using a vertical band window transom for connecting an upper window sash and a lower window sash together, with good workability, and to provide a vertical band window sash using the single window sashes.

The single window sash or the vertical band window sash which is a combination of the single window sashes is selectively formed below a bottom rail 2 or above an top rail 1, or below the bottom rail 2 and above the top rail 1. In one aspect, to form a sash framework structure of the single window sash, an engaging portion of a first attachment 5 is engaged with an engagement receiving portion 2a at a lower portion of the bottom rail 2 to attach the first attachment 5 to the bottom rail 2. Alternatively, in another aspect, to form the sash framework structure of the vertical band window sash, first and second engaging portions 6a, 6b, 6d, 6e of a second attachment 6 are engaged with engagement receiving portions 1a, 1b at upper portions of the top rail 1 and the engagement receiving portion 2a and an engagement receiving portion 2b of the bottom rail 2, and the bottom rail 2 and the top rail 1 are connected together by the second attachment 6.