PURPOSE: To provide a catalyst added in a process for producing lactide from a lactic acid prepolymer or lactic ester and exhibiting an excellent catalytic effect when lactide having low hygroscopicity is efficiently produced without using a large quantity of heat by using a specified dibutyl tin compd.

CONSTITUTION: This lactidation catalyst added in a process for producing lactide from a lactic acid prepolymer or lactic ester is a dibutyl tin compd. represented by the formula (where each of A1 and A2 is F, Cl, acetoxy, 2- hydroxypropionyloxy, methanesulfonyloxy or toluene sulfonyloxy or -A1 and -A2 are =0 in combination). When this catalyst is used, efficient production of lactide can be carried out without using a large quantity of heat and high purity lactide having low hygroscopicity can be produced in a high yield.