Formaldehyde, an indoor volatile organic compound, is considered toxic due to its carcinogenic risk. Recently, we isolated a formaldehyde-degrading bacterium Pseudomonas sp. YK-32. A crude enzyme prepared from YK-32 also degraded formaldehyde, suggesting that YK-32 cells have formaldehyde hydrogenase activity which is one of the important factors in formaldehyde degradation. The formaldehyde hydrogenase activity was increased 1.25 fold by adding 0.1 % glucose and formaldehyde to the culture medium. In addition, treatment with 1 mM EDTA as a permeabilizer promoted the degradation of formaldehyde and increased the enzymatic activity.