Larvae of the black soldier fly, Hermetia illucens are well‐known fly larvae that inhabit many countries around the world. Antimicrobial agents derived from the larvae may be among the substances that are produced in the body for their survival. This study was carried out to identify the antimicrobial effects of H. illucens larvae that commonly inhabit animal waste and food waste. To evaluate the pharmacological effects of H. illucens larvae extracts, the larvae were extracted by various organic solvents, and their antibacterial effects were determined by antimicrobial methods, such as agar disk diffusion and turbidometric assays. The methanol extracts (ME) indicated antibacterial effects against the proliferation of Klebsiella pneumoniae, Neisseria gonorrhoeae and Shigella sonnei. However, antibacterial effects were not induced in Gram‐positive bacteria such as Bacillus subtilis, Streptococcus mutans and Sarcina lutea. The bacterial growth treated with ME was strongly inhibited from 20 mg/mL in a dose‐dependent manner compared with other extracts, and antibacterial activity gradually decreased after 24 h. Moreover, the minimal inhibitory concentration (MIC) values of ME against Klebsiella pneumoniae, Neisseria gonorrhoeae and Shigella sonnei for 12 h were measured as 44.74 mg/mL, 43.98 mg/mL and 43.96 mg/mL, respectively. These results demonstrate that ME of H. illucens larvae not only has antibacterial activity which strongly inhibits the growth and proliferation of the bacteria but also unique properties which effectively block the viability of the bacteria.