PURPOSE: To provide a lead-free gasoline which can improve combustion stability and reduce the amt. of unburnt hydrocarbons discharged in a lean burn engine.

CONSTITUTION: A lead-free gasoline comprises a gasoline composition having an octane value of not less than 85 as measured by the research method, a Reid vapor pressure(RVP) of 0.45 to 0.95kgf/cm2, a density at 15°C of 0.65 to 0.8g/cm3, a 50% recovered temp. of 90°C or below, a 70°C recovery of not less than 25vol%, a total content of 7 C or higher arom. hydrocarbons and 7 C or higher olefins of not more than 5vol%, and a total content of 6 C or lower paraffins having no side chain, benzene, 6 C or lower olefins, and 6 C or lower naphthenes of not less than 20vol%, and optionally 5 to 50vol% oxygen-contg. compd. having a ratio of the number of oxygen atoms to the number of carbon atoms (O/C number ratio) of not less than 0.5.