An integral composite fiber is formed by integrally joining a stretchable fiber and unstretchable fibers. The stretchable fiber has longitudinally extending first exposed surfaces that are circumferentially spaced from each other. The unstretchable fibers has longitudinally extending second exposed surfaces each disposed between a circumferentially adjacent pair of the first exposed surfaces. One of the first exposed surfaces has a larger surface area than the other or others of the first exposed surfaces. Said other or each of the others of the first exposed surfaces has a surface area ratio of less than 0.8 with respect to the surface area of said one of the first exposed surfaces. By longitudinally stretching this integral composite fiber, because shear stress is large due to a large difference in shrinkage stress between said one of the first exposed surfaces and the other or others of the first exposed surfaces, the unstretchable fibers easily separate from the stretchable fiber, and are three-dimensionally crimped. The unshrinkable fibers are thus helically wrapped around and covers the shrinkable fiber, which has a rubber-like feel to the touch. Thus, the composite fiber obtained is bulky and feels good to the touch.