PROBLEM TO BE SOLVED: To provide a method for producing an onion processed product for an acid seasoning having a fresh feeling, suitable bitterness and pungency and sufficient flavor and not discolored when being added to an acid seasoning.SOLUTION: Provided is a method for producing an onion processed product for an acid seasoning containing the following step A and step B:the step A of heating a hole-shaped orion at the central temperature of 60 to 80°C using vapor and the step B of chopping or pasting the onion obtained in the step A.