Alstonia scholaris wood has a high potential as a raw material of the forestry industry, such as veneer, crates, matches, heels, masks, concrete molds, and pulp. The low durability of A. scholaris wood is a weak point that must be improved. One technique for improving the A. scholaris wood durability is giving it a treatment using ethanol extract of Cerbera manghas seed, which has antifungal and antibacterial abilities. The purpose of this study was to analyze the durability characteristics of A. scholaris wood treated with C. manghas seed ethanol extract. The experiment was carried out with a combination of C. manghas seed ethanol extract concentration with 5 levels (0%, 20%, 40%, 60%, and 80%). The durability analysis using the Schizophyllum commune for 12 weeks (SNI 01-7207-2006). The result shows that the differences in concentration of C. manghas seed ethanol extract had a significant effect on retention, absorption, and weight loss of A. scholaris wood. The giving of C. manghas seed ethanol extract concentrations both of 40% and 80% was able to increase the durability of A. scholaris wood. These concentrations increase the durable class into III and I, respectively. GC-MS analysis showed that the C. manghas seed ethanol extract contained 35 types of compounds. The five dominant types of compounds are: Octadecane (CAS) n-Octadecane, Nonadecane (CAS) n-Nonadecane, Heneicosane (CAS) n-Heneicosane, Tetratetracontane (CAS) n-Tetratetracontane, and Tetracontane, 3, 5, 24-trimethyl—(CAS).