We demonstrate the preparation of particles with a variety of inner structures from block-copolymers and polymer blends by using a simple solvent evaporation process. One-directionally stacked or onion-like lamellar structures were formed from symmetric block-copolymers. Asymmetric block-copolymers formed cylindrical phase in nanoparticles. “Janus”-type particles were prepared from homopolymer blends. A network structure was formed in the homopolymer blend particles containing block-copolymers, which work as compatibilizers for homopolymer blends.