The invention provides true La(OiPr)₃ preferable as a starting material for an asymmetric synthesis catalyst and a process for producing the same. In this process, anhydrous lanthanum chloride LaCl₃ is reacted with potassium isopropoxide K(OiPr) in a mixed solvent of isopropanol and toluene, then the isopropanol is distilled away to replace all the solvent by toluene, then the reaction solution is left, decanted and filtered to give a transparent filtrate, and the solvent is distilled away from the filtrate which is then vacuum-dried under heating, whereby high-purity La(OiPr)₃ is obtained in 77% yield. In this high-purity La(OiPr)₃, the La content is 97 to 103% of the theoretical content, impurity K is 0.3% or less, (Li+Na) is 0.01% or less, Cl is 0.2% or less, and the degree of association thereof is 5.5 to 6.5.