Disclosed are an apparatus (100) and a method for sterilizing aqueous solution using a flexible ultraviolet irradiator (20). An aqueous solution sterilizing apparatus (100) includes an aqueous solution flow tube (10) formed in a helical shape, configured to block exposure of ultraviolet rays from an inside of the aqueous solution flow tube to an outside thereof, and through which aqueous solution flows, and an ultraviolet irradiator (20) formed of a flexible material (23) to be inserted inside the aqueous solution flow tube (10) and configured to irradiate the aqueous solution with the ultraviolet rays to sterilize the aqueous solution.