In this study, melting behavior in comb-shaped aggregates of poly(4-vinylpheol (PVPh) and N,N-dimethyloctadecylamine (NDOA) with xylene which is a good solvent only for NDOA is investigated. For comb-shaped PVPh-NDOA aggregates with sufficient side chains, the melting temperature is simply depressed by addition of a small amount of xylene. Hence, xylene acts as only diluents for side chain crystals for PVPh-NDOA aggregates with sufficient side chains. On the other hand, it is found that for PVPh-NDOA aggregates with small portions of side chains the presence of a small amount of xylene caused elevation of melting temperature. Therefore, it is suggested that the presence of a small amount of good solvent for only side chains promotes assembly and rearrangement of alkyl chains of NDOA in the comb-shaped aggregates with small portions of side chains.