The bottom-up approach using self-assembly of block copolymers (BCP) has been considered as a powerful technique in nanolithography. For practical applications, the perpendicular orientation of microdomains to the substrate is a prerequisite. However, in most cases, one of domains has a preferential interaction with the substrate and induces parallel orientation. Previously, we demonstrated that thermally stable neutral Au NPs can induce perpendicular orientation of BCP thin films without any substrate treatment. In this study, we prepared a perpendicularly oriented poly(styrene-b-methyl methacrylate) (PS-b-PMMA) thin films by introducing neutral star copolymers consisting of PS-r-PMMA arms and divinylbenzene (DVB) core. The star copolymers were synthesized by arm-first method via atom transfer radical polymerization (ATRP). We varied the composition of MMA in PS-r-PMMA arms from 40 mol % to 80 mol % to confirm the optimal neutral composition of star copolymer for inducing the perpendicularly oriented BCP thin films. It was found that the star copolymer having an overall PS and PMMA composition of 59:41 exhibits the well-ordered perpendicular orientation of lamellar structures after thermal annealing. Furthermore, we also synthesized the deuterated star copolymers, which consist of dPS-r-dPMMA arm and DVB core to trace them within PS-b-PMMA films along the vertical direction by neutron reflectivity. In this case, it was observed that star copolymers were mainly located at the top surface and bottom interface of the films, thereby effectively neutralizing the surface/interfacial energy differences.