an object of the present invention is to provide a process for producing a β - amino - α - hydroxy acid derivative via efficient and industrially utilizable steps . the present invention provides a process for producing a β - amino - α - hydroxy acid derivative represented by the general formula given below which comprises hydrolyzing an α - amino - α &# 39 ;, α - dihaloketone derivative of the general formula given below in the presence of a base , followed by protecting the amino group or without protecting the same . ## str1 ##