[Problem] To provide effective use from a yeast extract residue, an excess of which is produced as a byproduct of yeast extract, or reduction in amount of the yeast extract residue. Also to obtain various useful substances. [Means for Solving the Problem] A cell wall lytic enzyme having no protease is allowed to act on a yeast extract residue, after which a heat treatment is performed at 70 to 80°C for 10 to 20 minutes, thereby enabling separation into a fraction of primarily cell walls and a fraction of primarily protein. A yeast protein having a protein content of 60% or more is obtained from the fraction of primarily protein and, by subjecting the yeast protein to enzymatic degradation, a seasoning having a high amount of total nitrogen is obtained.
