The main target of fatty acids is disrupting the electron transport chain and oxidative phosphorylation of bacterial cells. One of the fatty acid-producing microorganisms is Spirulina platensis. Therefore this study was aimed to determine the types of fatty acid compounds from S. platensis, which have the potential as antibacterial. Biomass is extracted by soxhlet using different polarity solvents (n-hexane, chloroform, ethyl acetate, and ethanol). An antibacterial activity using the paper disc diffusion method against Staphylococcus aureus and Escherichia coli. Identification of fatty acid compounds using Gas Chromatography-Spectrometry Mass (GC-MS). The antibacterial activity showed that chloroform extract showed the largest inhibition zone. Furthermore, chloroform extract was fractionated and simplifying fractions. The results of the identification of the best fraction showed that there were several types of fatty acids namely Hexadecanoic acid, methyl ester (10.99%), 1.2-Benzenedicarboxylic acid (0.74%), heptadecanoic acid, methyl ester (0.09%), 6.9.12-Oxiraneoctanoic acid (8.84%), 9,12-Octadecadienoic acid (0.52%), Octadecanoic acid, methyl ester(2.28%), Oxiraneoctanoic acid (8.86%), Eiocosanoic acid, methyl ester (0.46%), Hexanedioic acid, dioctyl ester (6.46%) and Docosanoic acid, methyl ester (0.26%). Based on this study, the fatty acids found in S. platensis have an ability to be naturally antibacterial. © 2020 Published under licence by IOP Publishing Ltd.