To enhance the photoluminescence (PL) from erbium-doped silicon, nanopillars were fabricated in a silicon-on-insulator (SOI) layer with erbium and oxygen. Photoluminescence measurements at room temperature demonstrated that a nanopillar with the diameter of 1435 nm exhibits the highest near-infrared PL from erbium atoms, which is 2.0 times higher than that from an unstructured erbium-doped SOI layer. Optical simulations revealed that the PL enhancement is mainly due to the resonance absorption of excitation light at the wavelength of 785 nm. The results show the potential of nanostructure fabrication for enhancing the near-infrared PL intensity.