Provided is a method for industrially producing a triazolidinedione compound at a high purity and a high yield. A precipitation step for preparing a solution that contains a triazolidinedione compound represented by formula (1) and precipitating the triazolidinedione compound therefrom is performed. In this step, the pH of the solution is adjusted to 3.0 to 8.5 and the solution is prepared so as to contain 3-15 parts by volume of solvents for 1 part by mass of the triazolidinedione compound. (In the formula, R1 is a substituted or unsubstituted amino group-bearing organic group.)