Abstract We measured resonant inelastic X-ray scattering spectra of one-dimensional Mott insulator Sr2CuO3 near the Cu 1s absorption edge ( h ν ∼ 8.999 keV) for the purpose of observing the interband transitions between the occupied bands and the unoccupied bands. The obtained RIXS spectra have shown dispersions depending on the wave number difference Δ k from Δ k = 2.25 π to 3.75 π along the single Cu O chain. Each spectrum shows two main features, one is at around 5.5 eV and the other at around 3.1 eV for Δ k = 3.0 π . The 5.5 eV feature does not show noticeable Δ k dependence and can be interpreted as a charge transfer excitation from the Cu 3d–O 2p antibonding state to the upper Hubbard band (UHB). The feature observed near 3.1 eV for Δ k = 3.0 π shows prominent Δ k dependence. The energy loss is the largest near Δ k = 3.0 π and 5.0 π and the smallest near Δ k = 2.0 π and 4 π . This structure is interpreted as the excitation from the Zhang–Rice singlet to the UHB.