To provide a rail member for a sideboard, which establishes compatibility between the function of attaching a functional plate and the function of covering an intermediate plate and the functional plate.

A rail member for a sideboard, which is provided at a front end of an intermediate plate for vertically partitioning the sideboard and which travelably supports a sliding door, comprises a rail part, a hook-like attachment part that is positioned on the back end side of the rail part and attached to the front end of the intermediate plate, and a functional plate supporting part that is positioned in the lower part of the hook-like attachment part and that supports a front end of a functional plate. The rail member concurrently achieves both the function of attaching the functional plate and the function of covering the intermediate plate and the functional plate.