Provided is a method for manufacturing a base material powder having a carbon nanocoating layer, the method including adding a polycyclic aromatic hydrocarbon to a base material powder, heating the mixture to a temperature that is higher than or equal to the boiling point of the polycyclic aromatic hydrocarbon and is lower than or equal to the relevant boiling point temperature+300° C., and that is higher than or equal to the thermal decomposition temperature of the polycyclic aromatic hydrocarbon, and thereby coating the surface of the base material powder with a layer of carbon having a thickness of 0.1 nm to 10 nm. According to the method, when a source of carbon that covers a base material powder is appropriately selected, the base material powder having the carbon nanocoating layer can be provided, which does not have a possibility of causing inconveniences in the applications of a final manufactured product of the base material powder and exhibits satisfactory productivity of the base material powder, and from which a modified final manufactured product is obtained.