White-rot basidiomycetes produce extracellular ligninolytic enzymes that are able to degrade not only lignin but also xenobiotics such as PCBs, dioxins and bisphenol compounds. The degradation rate constants of xenobiotics vary depending on their chemical structure. This study aimed to analyze the effect of chemical structure on the rate constant of degradation of mono-substituted benzenes by the white-rot basidiomycete Coriolus hirsutus IFO 4917. The linear relation representing the Hammett equation was confirmed in the log-log plot of the degradation rate constants of aniline, phenol and benzaldehyde and their acid dissociation constants. The log-log plots showed a negative slope. The experimental results strongly suggest that the substitution of an electron-withdrawing group into benzene decreases the biodegradation rate constant. A mathematical model to estimate the biodegradation rates of the mono-substituted benzenes was formulated.