A three-piece solid golf ball comprising an inner core 1a, an outer core 1b, and a cover formed principally of an ionomer resin, wherein said inner core 1a has a diameter of 10 to 38 mm, said outer core 1b has a specific gravity of 0.2 to 0.79 and has a diameter of 37 to 40 mm and a total weight of the inner core 1a and the outer core 1b is within the range of 32.0 to 39.0 g.