The photoconduction (PC) mechanism in indium nitride (InN) nanowires (NWs) has been investigated via environment-, temperature-, and power-dependent measurements. The adsorbed oxygen-induced modulation of the surface state is proposed to be the leading factor in the long lifetime or high gain transport and in sensitizing photocurrent generation in the InN NWs. The electron trapping effect by adsorbed oxygen can be verified by the increased activation energy from 33 ± 4 (in vacuum) to 58 ± 2 meV (in oxygen). The observed supralinear power dependence of photocurrent also suggests the presence of acceptor states that influence the carrier recombination behavior and compensate the thermal carriers in the InN NWs. The potential influence of native oxide on the molecule-sensitive PC in this nitride nanomaterial is also inferred.