A vehicle frame structure for a saddle-type vehicle has a vehicle frame including a subframe portion detachably mounted on a main frame, and a joint between the main frame and the subframe which is disposed in a longitudinally intermediate portion of a continuously extending frame component, wherein the frame component is kept rigid and the joint is maintained in a small size. In the joint, the frame component has a portion divided by a vertical plane into a main-frame-side joint arm and a subframe-side joint arm. The joint arms have distal ends having arcuate outer walls cut off around their fastening positions. The joint arms further have integral upstanding walls disposed on proximal ends thereof, corresponding to the cut-off arcuate outer walls of the joint arms. The joint arms are fastened to each other with the distal ends thereof fitted in cavities surrounded by the upstanding walls.