A colorless pillar crystalline component, m.p. 207° (decomp.), [α]_D+80.0°(H₂O), C₅H₈O₄N₂ of good flavor without smell, and of having insecticidal property was isolated from Tricholoma muscarium KAWAMURA (Jap. name: Haetorishimeji) in the process illustrated in Fig. 1. The compound was considered to be acidic amino acid, still unknown substance, which named tricholomic acid.