In recent years, biodegradable plastics have increasingly been adopted as alternatives to petroleum-based plastics to mitigate environmental pollution. Among these, polyhydroxybutyrate (PHB) is particularly favored due to its considerable strength and durability. However, the anticipated mass production and widespread use of biodegradable plastics may introduce new environmental challenges related to their decomposition. To address this issue, we isolated Comamonas sp. C10, an aerobic microorganism, from wood fragments around Mt. Kurodake in Japan and confirmed its capability to degrade PHB. While genetic modification could enhance degradation, it raises ecological concerns when applied to natural ecosystems. Recent findings by Cao et al. (2024) suggest that biodegradable microplastics may have equal or greater ecotoxicity than traditional plastics, making their rapid decomposition a pressing issue. This study employed Adaptive Laboratory Evolution (ALE) to investigate enhancements in PHB degradation. We incrementally increased PHB concentrations to 0.2%, 0.5%, and 0.8% during ALE. Once degradation rates exceeded 80% at each concentration, we conducted further degradation experiments using adapted cultures at higher PHB concentrations. The ALE-induced samples exhibited a degradation rate exceeding 60% within 48 hours, while the non-ALE-induced samples showed a degradation rate of approximately 36% over the same period. These results indicate that the degradation rate of ALE-induced samples is approximately 1.7 times higher than that of non-ALE-induced samples, highlighting the effectiveness of ALE. Additionally, experiments comparing the degradation rates with and without ALE induction using crude extracellular enzymes from strain C10 demonstrated that PHB degradation was consistently faster in the presence of ALE induction across all concentrations. This suggests that the enhanced degradation rate of strain C10 induced by ALE is attributable to the increased activity of its extracellular enzymes. In conclusion, our findings indicate that the ALE method is effective in enhancing the PHB degradation activity of Comamonas sp. C10, presenting a promising approach for improving the environmental performance of biodegradable plastics.