The Second Republic of Korea refers to the political system and government of South Korea that was established after the April Revolution of 1960, which led to the resignation of President Syngman Rhee and the end of the First Republic of Korea. The April Revolution was a series of mass protests that were sparked by the discovery of the body of a local high school student who had been killed by police during demonstrations against rigged elections in March. The Second Republic of Korea was established after the fall of the Rhee government and his replacement by President Yun Posun.

The Second Republic was marked by a transition towards democracy, with a new constitution adopted in October, 1960 which provided for a separation of powers, a bicameral legislature, and a strong presidency. The government under the Second Republic was characterized by a shift from authoritarian rule to a more democratic system with free and fair elections, civil liberties, and a free press.

However, the Second Republic also had its challenges, including political instability and economic difficulties, which led to a series of coups d'etat, and military dictatorship led by Park Chung-hee which lasted until 1979. It was followed by the Third Republic of South Korea which was a democratic government that lasted until 1987.