Anthocephalusmacrophyllus (Roxb.) Havil. seedlings are the most preferred plant for nursery because they have a lot of benefits. Further, its benefits can increase economic prosperity of this plant. The main problem in nursery of forestry plants is pest and disease attacks. The disease that is a focus on this research is dieback disease. The dieback disease is caused by Botryodiplodiatheobromae Pat. that may lead the host plant to death. Every plant has its resistant mechanisms to pathogen attacks both before and after pathogen attacks. This research aims: (1) to study B. theobromaeattack with wounded and non-wounded stem infection methods on red jabon seedlings; (2) to study resistant mechanism of red jabon seedlings both in structural and biochemical resistance against B. theobromae attacks. The structural resistance was done by studying the microscopic stem of the red jabon seedlings, which was conducted through scanning electron microscope. While, the biochemical resistance was done by studying the chemical compounds of red jabon seedlings’ stem using phytochemistry analysis. Red jabon seedlings had the structure of trychomaes on the epidermis and necrotic resistance as structural resistance before and after pathogen attacked, respectively. Red jabon seedlings also had secondary metabolites such as flavonoid, phenol hydroquinone, tannin, saponin, triterpenoids and steroids. Biochemical resistance of red jabon seedling after pathogen attacks showed the increase of accumulation of phenolic compounds as phenol hydroquinone and tannin and the increase of accumulation of triterpenoids and steroids compounds. A post-publication change was made to this article on 11 Mar 2020 to correct the conference title in the PDF header.