Four types of morphologie, lamellar, ordered tricontinuous double-diamond (OTDD), cylindrical, and spherical structures, of isoprene (I)-styrene (S)-2-vinylpyridine (P) triblock copolymers having I and P block polymers with the same volume fractions, were studied by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). These studies revealed that the spherical structure has the packing manner of the CsCl type consisting of two spherical domains of I and P end-block polymers and the cylindrical structure, which consists of two kinds of cylindrical domains of end-block polymers, has the tetragonally-coarrayed pattern. Moreover, the OTDD structure proposed previously was confirmed by TEM observation of one (P domains) of the double-diamond frameworks in a film specimen stained with phosphotungstic acid. From these results, together with the TEM and SAXS studies on three-phase four-layer lamellar structure, we conclude that the morphologies of the triblock copolymers used in this work have the characteristics of superlattice structures.