The worldwide production of plastics has increased considerably since the development of synthetic polymers in the middle of the 20th century. When discarded in the marine environment, plastics can become an environmental hazard. Plastic debris enters the marine environment in a wide range of sizes, in the micrometer to meter range. Microplastic particles comprise either manufactured plastics of microscopic size, such as scrubbers and industrial pellets that serve as precursors for manufactured plastic products (primary sources), or fragments or fibers of plastics derived from the breakdown of larger plastic products (secondary sources). Degradation processes of plastics are extremely slow, and thus microplastics potentially persist for very long time periods in the marine environment. Fourier transform infrared (FTIR) spectroscopy is a nondestructive and rapid method of analysis. FTIR spectrometry is widely used for polymer identification, and, more recently, ATR–FTIR (Attenuated Total Reflection) has been shown to give excellent results. Plastic polymers possess highly specific IR spectra with distinct band patterns making IR spectroscopy an optimal technique for the identification of microplastics. Six types of plastics were characterized in this paper from vibrational point of view. Biodegradable plastics are desirable alternatives to synthetic plastics which have led to serious problems of solid waste pollution. Four kinds of biodegradable plastics, such as poly (lactic acid), poly (butylenes adipate-co-terephthalate)-PBAT, poly (butylenes succinate) and poly (hydroxybutyrate-cohydroxyvalerate), are used more and more in everyday life. Using ATR–FTIR method we identified that the sample of biodegradable bag has mostly the same composition with PBAT biodegradable plastic.