In order to develop a life cycle assessment method, which can be widely applied to electrical appliances and office automation equipment we have investigated resource depletion, energy consumption, and environmental pollution in the manufacturing process of circuit boards, and we have identified the common units, such as 228 Mcal/kg of energy consumption and 15.979 kg-C/kg of carbon dioxide emission. Using these common units, we have calculated the categorized impact for the environment (resource depletion, global warming, acid rain, and atmospheric pollution) using a laptop personal computer, whose processing speed (PS) is improved by 5 times, weight is decreased by 47%, and energy-consumption is cut by 44%, compared with previous type. We have also shown that the life cycle environmental impact (EI) per personal computer decreases by 38% in resource depletion, life cycle EI per processing speed decreases 87% in all categories, and environmental efficiency (=PS/EI) in all categories improves by a factor of approximately eight (factor value: 8).