In this study, the effect of silica (Si) or titanium dioxide (Ti) on the extrusion behavior of styrene-butadiene rubber (SBR) was investigated. The complex viscosity of SBR, acquired from linear viscoelasticity, increased with the addition of Si or Ti, and the addition effect of Si on the complex viscosity was larger than that of Ti. On the other hand, the shear stress of SBR, evaluated using a capillary rheometer, slightly increased with the addition of Si, whereas that of SBR decreased with the addition of Ti. The roughness on the extrudate surface of SBR was suppressed with the addition of Si or Ti in the capillary flow test. Focusing on the effect on the surface roughness by the wall slip while flowing in the capillary, the wall slip velocity of each sample was calculated from the analysis of pressure flow in the capillary. From the relationship between the surface roughness and the wall slip velocity, the addition of Si or Ti results in the suppression of the extrudate of SBR to the surface roughness due to promoting the wall slip. Therefore, it was concluded that the Si and Ti contributed to the wall slip of SBR in the shear flow, and the wall slip suppressed the surface roughness of the SBR extrudate.