To construct a sliding element so as to allow a small radius of curva ture in a guide passage for the sliding element in spite of installation of a branch area in a guide rail.

This openable roof for a vehicle is provided with a first supporting member 20 for a first movable cover 22 guided in the roof longitudinal direction freely slidably by means of a first sliding element 18 along a guide rail 10 fixed to the roof. The guide rail 10 is provided with a main path 12 having a first side wall 38 and a second side wall 40, which face each other for guiding the first sliding element 18 by a mutual reaction on the side wall inside faces, and an auxiliary path 34 branched from the second side wall 40 inside a branch area 14. The first supporting member 20 is provided with a second sliding element 36 cooperating with the first sliding element 18 by the contact to the outside face of the first side wall 38 in the branch area 14. As the result of this cooperation, the first sliding element 18 is guided to the main path 12 along the inside face of the first side wall 38 and prevented from entering the auxiliary path 34.