This method for producing a crosslinked product of a carboxymethyl-group-containing modified hyaluronic acid includes a step for keeping a solution comprising a carboxymethyl-group-containing modified hyaluronic acid and/or a salt thereof between -200 DEG C and 10 DEG C, inclusive.本發明為一種含有羧甲基之修飾玻尿酸之交聯物之製造方法,其係包含將含有羧甲基之修飾玻尿酸及/或其鹽之溶液保持在-200℃以上且10℃以下之步驟。