Constraints imposed by nanometer-scale confinement leads to the changes in the bulk equilibrium behavior of block copolymers (BCPs). Cylindrical pores with diameters corresponding to the length equivalent to several multiples of copolymer chain size have been employed to investigate the influence of two-dimensional confinement on the behavior of BCPs. In the present study, we expand the scope of nano-confinement to homopolymer-BCP blends. Given a fraction of homopolymers, the phase behavior of BCP in bulk phase is dependent on the molecular weight (Mw) of homopolymers. While low Mw homopolymers make phase transitions so as to increase the curvature of micro-domains of a minor phase, homopolymers with high Mw extend the center-to-center distance of domains and eventually induce the macro-phase separation. In the present study, lamella-forming BCPs of poly(styrene-b-butadiene)(PS-b-PBD) mixed with homopolymers of PS or PBD were drawn, in the melt, into the pores of anodized aluminum oxide (AAO) membranes by the capillary force. Based on the detailed observation of BCP self-assembly within the porous columns, we analyzed the structural transition of BCPs induced by the presence of homopolymers and confinement. The effect of homopolymers on the micro-domain morphologies of BCPs is greatly amplified in the nanoscale confinement compared with the bulk state due to the frustration which polymer chains experience. We also report the effects of PS and PBD homopolymers on the microdomain morphology of BCPs caused by the differential affinity between homopolymers and AAO.