Ritsuryō (律令; Japanese: [ɾi.tsɯ.ɾʲoː, ɾi.tsɯ.ɾei, ɾi.tsɯ.ɾeː]) is the historical legal system based on the philosophies of Confucianism and Chinese Legalism in Feudal Japan. The political system in accord to Ritsuryō is called "Ritsuryō-sei" (律令制). Kyaku (格) are amendments of Ritsuryō, Shiki (式) are enactments.

Ritsuryō defines both a criminal code (律, Ritsu) and an administrative code (令, Ryō).

During the late Asuka period (late 6th century – 710) and Nara period (710–794), the Imperial Court in Kyoto, trying to replicate China's rigorous political system from the Tang dynasty, created and enforced some collections of Ritsuryō. Over the course of centuries, the ritsuryō state produced more and more information which was carefully archived; however, with the passage of time in the Heian period, ritsuryō institutions evolved into a political and cultural system without feedback.

In 645, the Taika reforms were the first signs of implementation of the system.

Major re-statements of Ritsuryō included the following:

In the later half of the seventh century, the Kokugunri system (国郡里制, kokugunri-sei) was introduced, dividing the regions of Japan into several administrative divisions.

In 715 CE, the Gōri system (郷里制, gōri-sei) was introduced, resulting in the following.

This system was abandoned in 740 CE.