Mangrove Avicennia sp. an important mangrove species, because it used as traditional medicine. This research aimed to obtain a fraction of mangrove leaves extract Avicennia sp. which has antibacterial bioactivity against S. aureus and E. coli. Mangrove leaves collected from the coast in the village of Kabonga Besar, Donggala District, Central Sulawesi. Antibacterial activity assayed using the agar diffusion well method. The results showed the presence of steroid, triterpenoids, flavonoids, alkaloids and polyphenols compounds. Antibacterial activity showed by ethyl acetate fraction (S. aureus 16.97 ± 1.15 mm and E. coli 14.40 ± 0.46 mm) and ethanol (S. aureus 12.20 ± 2.12 mm and E. coli 8.13 ± 0.42 mm) at 1,000 mg/mL. This study has explored the antibacterial ability of Avicennia sp. leaves extract in n-hexane, ethyl acetate, and ethanol. Phytochemical analysis of various solvent extracts shows that flavonoids and tannins are common in all plant extracts with antibacterial properties. Avicennia sp. leaves extract can be used to find new bioactive natural products and can use as a potential source that can control pathogenic bacteria.