To provide a sash window which prevents a sash from coming off in cleaning etc., while adapting to a barrier-free window, which enables the sash to be smoothly operated for opening/closing, and which has excellent appearance designability.

Since a rail part 30, an airtight material 31, and an upper end of a between-rails top-surface member 32 are provided in positions to be almost flush with one another, a top surface of a sill 12 can be flatly formed, and the barrier-free sash window can be constituted. Since a section between the rail parts 30 can be cleaned by removing the member 32, cleaning work can be performed with ease, without the risk that the sash 15 may come off in the cleaning. Furthermore, various types of designs are applied to the member 32, so that the appearance designability of the sill 12 can be enhanced.