Introduction: Pseudomonas aeruginosa bacteria can form biofilms in body tissues and cause many infectious diseases. This study aims to determine the effect of exposure to ozone and laser diode 403 nm at various ozone concentrations and energy density on the inactivation effectiveness of Pseudomonas aeruginosa ATCC 27853 biofilm. Methods: Samples were divided into 4 groups, namely C0 control group without treatment, T1 ozone treatment group. , T2 diode laser treatment group and T3 ozone treatment group with diode laser. Treatment used a 403 nm diode laser with a biofilm age of 48 hours. Results: The results of statistical tests showed that there was a significant photoinactivation effect on the percentage reduction of Pseudomonas aeruginosa bacterial biofilm. Optimal treatment in the 0.011 mg / L ozone exposure group with a flow time of 80 s resulted in a 42.77% reduction in biofilm. Optimal laser treatment at an energy density of 4.99 J / cm2 for 300s long radiation time with 57.80% reduction percent. The combination of a 0.008 mg / L ozone treatment and a diode laser with an energy density of 4.99 J / cm2 resulted in a 78.74% reduction in percentage, which was significantly different from the other treatment groups. So the combination of ozone treatment with a diode laser is effective in reducing the biofilm Pseudomonas aeruginosa bacteria.