There is provided a vehicle frame structure for a motorcycle having an appealing appearance, which structure can be assembled lightweight and compact in size and at a reduced cost. The vehicle frame structure includes a head block (2) including a head tube (3), a main frame (11) forked leftwards and rightwards from the head block (2) to form a pair of main frame half portions (11a, 11b) extending rearwardly thereof, and swing arm brackets (8) extending downwardly from rear ends of the main frame half portions (11a, 11b). An inner frame portion (21) of the main frame (11) and the swing arm brackets (8) in their entirety or respective inner portions of the swing arm brackets (8) are integrally formed by an inner member (19) prepared from a metal casting, and at least an outer frame portion of the main frame (11) is formed by an outer member (20) prepared from a sheet metal.