The temperature dependence of conduction mechanisms in pure NiPS3 has been investigated by means of conductivity, photoconductivity, and thermopower measurements. Evidence for a p-type conduction has been found from the thermoelectric power data. The observed activated behaviors of thermopower, dark conductivities, and photoconductivities have allowed us to deduce more detailed information about the distribution of the electronic density of states in the energy-gap region. The results, fitted by assuming a single conduction path through extended-band states, have been interpreted in terms of an energy-band scheme based on a model regarding as insignificant the contribution of the 3d transition-metal states in bond.