NOVELTY - Two-step esterification process for production of biodiesel involves degumming and dehydrating waste oil as raw material, providing raw material to reactor, providing sulfuric acid and methanol to the reactor, reacting until the acid value becomes less than 2, providing resultant product into sedimentation tank, providing clean oil from sedimentation tank into reactor, separating impurities, providing solid sodium hydroxide and methanol mixture into the reactor, reacting until acid value becomes less than 3, and removing glycerol as biodiesel oil product from the sedimentation tank.    USE - Two-step esterification for production of biodiesel (claimed).    ADVANTAGE - The method enables production of biodiesel with high purity and high yield.    DETAILED DESCRIPTION - Two-step esterification for production of biodiesel involves degumming and dehydrating waste oil as raw material, purifying the raw material, then providing the raw material from feedstock measuring tank to reactor by gear pump, then providing 98% sulfuric acid from sulfuric acid metering tank to the reactor through discharge valve, providing methanol from methanol metering tank to the reactor, reacting the resultant product at 68-72 degrees C for 3 hours until the acid value becomes less than 2, increasing the temperature of the reactor to 85-95 degrees C, in which excess methanol steam is provided into methanol recovery tower, providing the resultant product into sedimentation tank by anticorrosive pump for 8-10 hours, in which impurities are deposited on the lower surface of the tank and clean oil on the upper layer, then providing clean oil from sedimentation tank into the reactor through anticorrosive pump or gear pump using alkali, separating impurities using sulfuric acid and water, then providing the resultant product into sewage treatment system, then providing solid sodium hydroxide and methanol into a mixer, mixing, then providing the mixture into the reactor, reacting the resultant product at 70 degrees C until the acid value becomes less than 3, providing the resultant product into multilayered evaporator provided with preheater, heating the evaporator using steam to remove excess of methanol which is sent to the methanol recovery tower, providing the resultant product into sedimentation tank to separate glycerol in lower layer and clean oil in upper layer, removing glycerol as biodiesel oil product, and providing the resultant product into refining plant and glycerol tank. The concentration of sulfuric acid in material is 3%. The molar ratio of methanol with respect to free fatty acid raw material is 1-10. The content of solid sodium hydroxide is 1% with respect to total content of the material. The molar ratio of methanol with respect to triglyceride is 15-1. An INDEPENDENT CLAIM is included for biodiesel production apparatus.