Indonesia as a legal state and a country with the largest Muslim population in ASEAN has regulation of adultery. Regulation of adultery can be found in Indonesian Criminal Code. However, do the regulation can solve the adultery issues. It is apparently not, Indonesia has some specific requirements to qualify as adultery. Adultery must be commited by one party that is bound to the marriage. While if the adultery is committed by a person who is not legally married is not regulated. It should be noted also that adultery in the context of the Indonesian Criminal Code is included into a complaint. Islam answered questions about adultery. As we know Islam has Islamic laws and the strict rules on adultery. In Islam, adultery is included into major sins. People who have sex without marriage or one of the parties who is legally married commits it will be accused in adultery category. The consequence for Indonesia; as the country with Islam as major religion, in judging an adultery case is by adopting Islamic values in the draft of Criminal Code. Harmonization is needed to be applied by Indonesia in view of Indonesian Code of Civil Law was the legacy of Dutch colonial; thus, the social values are conflicting with the culture and the religion of Islam in Indonesia. The problem is : do the adoption and harmonization can be accepted in Indonesian positively today.