The article describes the sources of contemporary Indonesian law and its structure. The Author explains that although the statutory law enjoys a predominant position in Indonesian legal system, it comprises also Islamic law and customary law (adat). This legal diversity has existed from the times of colonialism until today. Examples of it can be found both in legislative acts and courts rulings. Nevertheless, the influence of Islamic law and customary law (adat) is not identical in all Indonesian regions and there are some regions where this diversity is easier to notice (Aceh etc.).