Provided is a microfluidic device that can automatically perform various types of biological blood analysis. In the microfluidic device, a specimen is centrifugally separated and the centrifugally separated specimen is diluted into various dilution ratios. Also, at least two reagents that are required for one reaction and that need to be separately stored are stored in separate chambers, and they are mixed when a reaction is needed. Thus, various conventional blood analyzing reagents can be used as they are or after being minimally processed in the microfluidic device.