Potential energy curves for the lowest 3 Σ − , 3 Π, 1 Δ, and 5 Σ − states of NaN have been calculated by the multireference singles and doubles configuration interaction method, including Davidson’s correction for quadruple excitations (MR-SDCI(+Q)). It is shown that the former three are bound states, while the last one has no minimum. The ground state of NaN is predicted to be 3 Σ − for which the binding energy is evaluated as 0.859eV, and the rotational constants are calculated as B e =11.632 and B 0 =11.558GHz. The spectroscopic constants presented here will help in the detection of NaN in interstellar space.