To provide an oil-based coating composition that shows good coating film-drying (quick drying) properties in no need of a drying promotion agent (catalyst), for example, heavy metal oxide or an organic solvent as a dilution drying accelerator with excellent safety to human bodies in an oil-based coating for timbers as both for the rough coat and for finish coat.

A mixture of 85-65 wt.% of perilla oil and 15-35 wt.% of tung oil is subjected to the anoxic reaction, followed by the oxic reaction to prepare the objective oil-based coating composition.