Based upon the direct measurement of bedrock motions, we proposed two models to predict the zero-damped velocity response spectra in the bedrock of the Tokyo metropolitan area for the period range from 0.1 to 10s. These models were derived separately analyzing acceleration records of category A and category B earthquakes. Category B earthquakes distributed in and around the Philippine Sea plate. The response spectra predicted from the two models differ several times at the periods around 0.5s for the same earthquake magnitude and hypocentral distance, while they come closer together at the periods longer than 1s. Proper prediction of the bedrock motion is impossible for this area so far as a single model is used, where all earthquakes are mixed up.