A roof rack device includes a base with a first through hole disposed on a car roof and two carrier members with a second through hole disposed on the base. The base is provided with pin and control members. The control member has a first buckle portion and a cam which pushes the pin member into the first and second through holes or out of the second through hole. The outer end of each carrier member has a lock seat with a second buckle portion. When the first and second buckle portions are engaged, the cam keeps the pin member in the first and second through holes and the carrier members are retracted. When the first and second buckle portions are disengaged, the cam acts on the pin member to disengage from the second through hole and the carrier members can be extended for dismounting the articles.