PURPOSE: To industrially and advantageously remove nearly the total amount of sulfur compounds by treating a hydrocarbon mixture containing the sulfur compounds with an N-alkylalkanolamine and then washing the resultant treatment product with water.

CONSTITUTION: An N-alkylalkanolamine (preferably N-methylethanolamine) in an amount of ≥0.5mol equiv., preferably 0.5-20mol equiv. based on sulfur compounds (e.g. carbon disulfide, hydrogen sulfide or mercaptans) is added to a hydrocarbon mixture containing the sulfur compounds and treatment is then carried out at 2-60°C, especially 2-40°C temperature, for preferably 30-120min. The treatment product is then washed with water in a volume of ≥0.1, preferably 0.2-1 based on the hydrocarbon mixture at 0-50°C, preferably 10-30°C temperature to pass the reaction product and N-alkylalkanolamine into the water layer. The aforementioned method is effective in treating a 5C fraction formed as a by-product in cracking crude oils or fractions thereof and producing ethylene.