The invention relates to laminaria japonica cakes and a making method thereof. The making method includes: cooking laminaria japonica in a sodium hydroxide solution, beating the cooked laminaria japonica into puree, processing the puree with acid and ultrasonic, and adding bifidobacterium or lactic streptococci strains into the processed laminaria japonica puree to perform fermentation. The making method has the advantages that the laminaria japonica puree is processed by the acid and ultrasonic, so that the laminaria japonica can be deodorized sufficiently; the beneficial bacterium strains are added into the processed laminaria japonica puree, so that the laminaria japonica cakes contain beneficial bacterium factors. The laminaria japonica cakes made by the method are free of laminaria japonica odor, have both the nutrition of traditional rice cakes and the nutrition of the laminaria japonica and are rich in dietary fibers and beneficial bacterium factors.