In recent years, recycling related laws have been enforced for the purpose of global environmental preservation, which in turn has increased the amount of recycled plastic products around us. This trend entails the needs of rapid and detailed analyses of recycled products. In such cases, sufficient information may be obtained by analyzing not the entire polymers but oligomers. Conventionally, oligomers are analyzed by combining rough separation using the dissolution/reprecipitation method, etc., and various chromatographic or spectroscopic techniques. On the other hand, recently MALDI-TOF mass spectrometers are extensively used for oligomer analysis. By using such instruments, the information of terminal groups and monomer units can be obtained rapidly. This article introduces an example analysis of polycarbonate, which was performed by combining rough separation of oligomers by the dissolution/reprecipitation method and measurement and analysis using the benchtop MALDI-TOF mass spectrometer "MALDI-8020".