There is provided a motorcycle frame structure including a head frame which extends rearward from a head pipe, and tank rails which are welded to the head frame and extends rearward. The head frame includes first bracket portions extending downward. The tank rails include second bracket portions extending downward. An engine is suspended by the first bracket portions and the second bracket portions. Each of the first bracket portions includes a front wall portion extending in a width direction of a motorcycle, and a pair of side wall portions extending rearward from both ends of the front wall portion so as to form a first space opened to a rear side.