Well-defined AB(2) and A(2)B type miktoarm star copolymers consisting of aromatic polyether arms as the A segment and polystyrene arms as the B segment were synthesized from trifunctional initiators. Atom transfer radical polymerization (ATRP) of styrene was carried out in the presence of 3,5-bis(1-bromoethyl)-4'-fluorobenzophenone as a trifunctional initiator, and then the terminal C-Br bond of the polymer was reduced with Bu3SnH. The obtained polystyrene macroinitiators were used for aromatic polyether segment construction via chain-growth condensation polymerization (CGCP). The GPC trace showed a clear shift toward the higher-molecular-weight region with retention of low polydispersity, and no peak was detected in the lower-molecular-weight region. Accordingly, the target AB(2) type miktoarm star copolymers were synthesized without step-growth polycondensation. The synthesis of A(2)B type miktoarm star copolymers was carried out similarly using 1-bromomethyl-3,5-bis(4-fluorobenzoyl)benzene as a trifunctional initiator. The A(2)B type miktoarm star copolymers, which contained two arms of aromatic polyether units with high crystallinity, exhibited higher solubility than AB type diblock copolymer or AB(2) type miktoarm star copolymers. As in the case of the AB type diblock copolymer, the AB(2) and A(2)B type miktoarm star copolymers self-assembled to form spheres of 150-600 urn diameter when a THF solution of the copolymers was allowed to dry on a glass plate. Similar spherical aggregates were obtained from a THF-methanol solution of the A(2)B type miktoarm star copolymer, whereas the AB(2) type afforded fiber-like structures under the same conditions.