A preparation process of polyhydroxycarboxylic acid having an inherent viscosity of 0.3 dl/g or more by dehydrating polycondensation of lactic acid containing hydroxycarboxylic acid in an organic solvent in the presence or absence of a catalyst, comprising using a hydroxycarboxylic acid raw material which comprises one or more impurities selected from the group consisting of methanol, ethanol, acetic acid, pyruvic acid, fumaric acid, methyl lactate, ethyl lactate and butyl lactate in a total amount of 0.3% by mole or less for the amount of said hydroxycarboxylic acid raw material.