The present invention relates to an apparatus for supporting a carrier using a roof bar 10 installed on a roof of a vehicle, the apparatus including: one or more guides 20 which are installed on the roof bar 10, and each have a spool shape and a guide groove 22; multiple rings 30 which are movably installed on rods 62 of one or more carrier supports 60 of a carrier 50 installed on a trunk lid of the vehicle, in which the one or more carrier supports 60 serve to support a load and rotate in conjunction with an operation of opening and closing the trunk lid, each of the multiple rings 30 has a groove 32 which is engaged with the guide 20 on the roof bar in a state in which the trunk lid is closed, and the groove 32 is separated from the guide 20 when the trunk lid is opened; and bolts 40 which are coupled to the rings 30 by a threaded engagement and penetrate the rings 30, respectively, in which the bolts 40 are tightened to fix the rings 30 so that the rings 30 are not moved after the rings 30 are moved to adjust an interval to the roof bar 10, the rings 30 are coupled and engaged with the guides 20 when the trunk lid is closed, and the rods 62, which constitute the carrier supports 60, are moved along the guide grooves 22 of the guides 20 when the trunk lid is opened.