A center-channel protector for a vehicle sash door is arranged between a main sash and a center channel. A body of the protector has an H-shaped upper-end surface which is compatible to cover the upper end of the center channel. The body integrally includes a pair of branch covering portions corresponding to a pair of branch portions constituting the center channel and a middle covering portion disposed between the branch covering portions so as to connect the both branch covering portions therewith. An engaging portion is provided with the body and is mechanically engaged, in a direction intersecting a vertical direction, with an engaged portion which is provided with a center channel side. In collaboration with the engaged portion, the engaging portion constitutes a fastening mechanism by which the protector is fastened on the center channel.