Recently, global warming and exhaustion of fossil resources are increasingly attended. Lignocellulosic biomass is recognized as carbon neutral resource. Therefore, it is promising technology to produce ethanol from lignocellulosics and use it as automobile fuel for the formation of a sustainable society. We are developing the process to produce ethanol from waste house wood. The process consists of pretreatment, first-stage hydrolysis, second-stage hydrolysis and fermentation of each hydrolysate. Before each fermentation, detoxification is carried out. Waste house wood contains impurities that inhibit hydrolysis and fermentation. We compared the components of each hydrolysate, and found some impurities exceed the permissible level in the hydrolysate of waste house wood. Pretreatment of hydrolysate increased ethanol yield.