A roller assembly for a trolley conveyor that moves along a rail track including a flange and a web, comprising: a pair of brackets that is placed respectively on both side of the rail track, that has the shape of cranks corresponding to each other and that comprises a mounting hole for installing a below-described shaft; a roller that is rotatably coupled to an upper end of the bracket so as to be mounted on the web and slide; and a shaft that penetrates the roller, that is coupled to the roller and that is inserted into and fixed to the mounting hole, characterised in that, a wedge is installed in the mounting hole and stretches end portions of the shaft, and the mounting hole comprises a holding projection for fixing the shaft therein, and the shaft comprises a holding hook that has the shape of a cantilever elastically deformable and corresponding to the holding projection, in an end portion thereof, the shaft comprises a body that has the shape of a rod extending in one direction, a stopper that is formed at one end of the body, and the holding hook that is provided at the other end of the body, a pair of the holding hooks is arranged in parallel, and a slit for elastic deformation is provided between the holding hooks, the wedge comprises a cover that is inserted into the mounting hole, a stretching protrusion that protrudes from one side of the cover, that is inserted into the slit and that stretches the end portions of the shaft, and a sealing protrusion that is formed on both sides of the stretching protrusion, that closely contacts the mounting hole and that prevents foreign substances from being introduced, wherein the mounting hole comprises a small diameter part through which the holding hook passes and a large diameter part on which the holding hook is mounted, the holding projection is formed between the small diameter part and large diameter part, wherein the holding hook has an end portion that is tapered such that the holding hook is elastically deformed when the holding hook contacts the small diameter part, wherein the holding hook is configured to have a width less than a diameter of the shaft, and the small diameter part comprises a protruding part that prevents the shaft from rotating while contacting a lateral surface of the holding hook, and wherein a lubricating groove is formed along a perimeter of the body. a pair of brackets that is placed respectively on both side of the rail track, that has the shape of cranks corresponding to each other and that comprises a mounting hole for installing a below-described shaft; a roller that is rotatably coupled to an upper end of the bracket so as to be mounted on the web and slide; and a shaft that penetrates the roller, that is coupled to the roller and that is inserted into and fixed to the mounting hole, characterised in that, a wedge is installed in the mounting hole and stretches end portions of the shaft, and the mounting hole comprises a holding projection for fixing the shaft therein, and the shaft comprises a holding hook that has the shape of a cantilever elastically deformable and corresponding to the holding projection, in an end portion thereof, the shaft comprises a body that has the shape of a rod extending in one direction, a stopper that is formed at one end of the body, and the holding hook that is provided at the other end of the body, a pair of the holding hooks is arranged in parallel, and a slit for elastic deformation is provided between the holding hooks, the wedge comprises a cover that is inserted into the mounting hole, a stretching protrusion that protrudes from one side of the cover, that is inserted into the slit and that stretches the end portions of the shaft, and a sealing protrusion that is formed on both sides of the stretching protrusion, that closely contacts the mounting hole and that prevents foreign substances from being introduced, wherein the mounting hole comprises a small diameter part through which the holding hook passes and a large diameter part on which the holding hook is mounted, the holding projection is formed between the small diameter part and large diameter part, wherein the holding hook has an end portion that is tapered such that the holding hook is elastically deformed when the holding hook contacts the small diameter part, wherein the holding hook is configured to have a width less than a diameter of the shaft, and the small diameter part comprises a protruding part that prevents the shaft from rotating while contacting a lateral surface of the holding hook, and wherein a lubricating groove is formed along a perimeter of the body.