The principles of criminalization, meaning the reasons and why a behavior is considered a crime, play a fundamental role in legitimizing criminal policy. The criminalization process will be valid and efficient when it is based on defensible justifications. In criminal literature, several principles such as expediency, legal moralism, legal patriarchy, the principle of harm, the principle of aggression, perfectionism, and the principle of necessity are recognized as general principles of criminalization. In the field of foreign exchange crimes, criminalization sometimes overlaps with monetary crimes and sometimes focuses specifically on foreign exchange. However, the principles of foreign exchange criminalization in Iranian law have not been codified and coherently explained so far. Accordingly, the central question of the present study is what legal and criminal policy principles govern foreign exchange criminalization. The research method is based on induction and analysis of legislative examples. The findings show that currency crimes in Iran are based on various principles, the most important of which include: preventing the promotion of gambling in the currency market, the need for transparency in financial flows, controlling the volume of liquidity, managing conflicts of interest, providing the country with the currency it needs, and responding to specific economic conditions. Accordingly, currency criminalization in Iran's criminal policy has not been based on a single basis, but rather on a combination of various principles.