PROBLEM TO BE SOLVED: To provide a freezing processing method of algae which can suppress odor unique to algae and prevent reduction of nutritive value.SOLUTION: A freezing processing method of algae includes: a washing step of washing harvested algae in faintly acid electrolytic water of pH 5-6.5 a cooling step of cooling the algae washed in the washing step to 0°C a first freezing step of cooling the algae after the cooling step from 0°C to -5°C within 15 minutes a storage temperature arrival step of cooling the algae after the first freezing step from -5°C to a state of a storage temperature within 30 minutes, where the storage state is -41°C to -39°C and a cryopreservation step of cryopreserving the algae after the storage temperature arrival step at the storage temperature for more than 1 hour.SELECTED DRAWING: None
