High concentrations of acetaldehyde are often observed in indoor environments. One possible source of this is acetaldehyde formation produced by ethanol from wood building materials. To characterize indoor acetaldehyde formation and propose methods for its reduction, chamber-based experiments were conducted in which alcohols were added to pulverized solid woods. The results indicated that acetaldehyde was generated from the ethanol-added wood materials, and softwoods, namely Japanese cedar, Japanese cypress, and Swedish redwood generated more acetaldehyde than the other three woods. The experiments using different types of alcohols of methanol, ethanol, 1-propanol, and 2-propanol revealed a tendency similar to the reported enzymatic profile of the higher plant-derived alcohol dehydrogenase. It was confirmed that acetaldehyde generation was reduced by treatment methods typically used for inactivating enzymes, namely chemical treatments using pyrazole, borate, and urea and thermal treatments. The findings suggest that the chemical and thermal treatment methods are useful to reduce acetaldehyde generation in indoor environments.